227 F.3d 450 (D.C. Cir. 2000)
United States Telecom Association, et al.,Petitionersv.Federal Communications Commission and United States of America, RespondentsAir Touch Communications, Inc., et al., Intervenors
Nos. 99-1442, 99-1466, 99-1475 and 99-1523
United States Court of Appeals FOR THE DISTRICT OF COLUMBIA CIRCUIT
Argued May 17, 2000Decided August 15, 2000

[Copyrighted Material Omitted]
On Petitions for Review of an Order of the Federal Communications Commission
Theodore B. Olson argued the cause for petitioners United  States Telecom Association, et al.  With him on the briefs were Eugene Scalia, John H. Harwood, II, Lynn R. Charytan, Michael Altschul, Jerry Berman, James X. Dempsey,  Lawrence E. Sarjeant, Linda L. Kent, John W. Hunter and  Julie E. Rones.
Gerard J. Waldron argued the cause for petitioners Electronic Privacy Information Center, et al.  With him on the  briefs were Kurt A. Wimmer, Carlos Perez-Albuerne, Lawrence A. Friedman, Kathleen A. Burdette, David L. Sobel and  Marc Rotenberg.
Stewart A. Baker, Thomas M. Barba, Matthew L. Stennes,  Mary McDermott, Brent H. Weingardt, Todd B. Lantor,  Robert A. Long Jr., Kevin C. Newsom, Robert B. McKenna  and Dan L. Poole were on the brief for intervenor Sprint  Spectrum, et al.
Philip L. Malet, William D. Wallace and William F. Adler  were on the brief for intervenors Globalstar, et al.
John E. Ingle, Deputy Associate General Counsel, Federal  Communications Commission, argued the cause for respondent Federal Communications Commission.  With him on the  brief were Christopher J. Wright, General Counsel, Laurence  N. Bourne and Lisa S. Gelb, Counsel.
James M. Carr, Counsel, entered an appearance.
Scott R. McIntosh, Attorney, U.S. Department of Justice,  argued the cause for respondent United States of America. With him on the brief were David W. Ogden, Acting Assistant  Attorney General, and Douglas N. Letter, Attorney.
Before:  Ginsburg, Randolph and Tatel, Circuit Judges.
Opinion for the Court filed by Circuit Judge Tatel.
Tatel, Circuit Judge:


1
The Communications Assistance for  Law Enforcement Act of 1994 requires telecommunications  carriers to ensure that their systems are technically capable  of enabling law enforcement agencies operating with proper  legal authority to intercept individual telephone calls and to  obtain certain "call-identifying information."  In this proceeding, telecommunications industry associations and privacy  rights organizations challenge those portions of the FCC's  implementing Order that require carriers to make available to  law enforcement agencies the location of antenna towers used  in wireless telephone calls, signaling information from custom  calling features (such as call forwarding and call waiting),  telephone numbers dialed after calls are connected, and data  pertaining to digital "packet-mode" communications.  According to petitioners, the Commission exceeded its statutory  authority, impermissibly expanded the types of callidentifying information that carriers must make accessible to  law enforcement agencies, and violated the statute's requirements that it protect communication privacy and minimize the  cost of implementing the Order.  With respect to the custom  calling features and dialed digits, we agree, vacate the relevant portions of the Order, and remand for further proceedings.  We deny the petitions for review with respect to  antenna tower location information and packet-mode data.


2
* The legal standard that law enforcement agencies  ("LEAs") must satisfy to obtain authorization for electronic  surveillance of telecommunications depends on whether they  seek to intercept telephone conversations or to secure a list of  the telephone numbers of incoming and outgoing calls on a  surveillance subject's line.  In order to intercept telephone  conversations, law enforcement agencies must obtain a warrant pursuant to Title III of the Omnibus Crime Control and  Safe Streets Act of 1968.  Before issuing a Title III wiretap  warrant, a judge must find that:  (1) "normal investigative  procedures have been tried and have failed or reasonably  appear to be unlikely to succeed if tried or to be too dangerous";  and (2) there is probable cause for believing "that an  individual is committing, has committed, or is about to commit" one of a list of specifically enumerated crimes, that the  wiretap will intercept particular communications about the  enumerated offense, and that the communications facilities to  be tapped are either being used in the commission of the  crime or are commonly used by the suspect.  18 U.S.C. § 2518(3).  The Electronic Communications Privacy Act of  1986 ("ECPA"), id. § 3121 et seq., establishes less demanding  standards for capturing telephone numbers through the use  of pen registers and trap and trace devices.  Pen registers  record telephone numbers of outgoing calls, see id. § 3127(3);trap and trace devices record telephone numbers from which  incoming calls originate, much like common caller-ID systems, see id. § 3127(4).  Although telephone numbers are not  protected by the Fourth Amendment, see Smith v. Maryland,  442 U.S. 735, 742-45 (1979), ECPA requires law enforcement  agencies to obtain court orders to install and use these  devices.  Rather than the strict probable cause showing  necessary for wiretaps, pen register orders require only  certification from a law enforcement officer that "the information likely to be obtained is relevant to an ongoing criminal  investigation."  18 U.S.C. § 3122(b)(2).


3
Wiretaps, pen registers and trap and trace devices worked  well as long as calls were placed using what has come to be  known as POTS or "plain old telephone service."  With the  development and proliferation of new telecommunications  technologies, however, electronic surveillance has become increasingly difficult.  In congressional hearings, the FBI identified 183 "specific instances in which law enforcement agencies were precluded due to technological impediments from  fully implementing authorized electronic surveillance (wiretaps, pen registers and trap and traces)."  H.R. Rep. No.  103-827, pt. 1, at 14-15 (1994).  These impediments stemmed  mainly from the limited capacity of cellular systems to accommodate large numbers of simultaneous intercepts as well as  from the growing use of custom calling features such as call  forwarding, call waiting, and speed dialing.  See id. at 14.


4
Finding that "new and emerging telecommunications technologies pose problems for law enforcement," id., Congress  enacted the Communications Assistance for Law Enforcement Act of 1994 "to preserve the government's ability,  pursuant to court order or other lawful authorization, to  intercept communications involving advanced technologies  such as digital or wireless transmission modes, or features  and services such as call forwarding, speed dialing and conference calling, while protecting the privacy of communications and without impeding the introduction of new technologies, features, and services," id. at 9.  Known as CALEA, the  Act requires telecommunications carriers and equipment  manufacturers to build into their networks technical capabilities to assist law enforcement with authorized interception of  communications and "call-identifying information."  See 47  U.S.C. § 1002.  The Act defines "call-identifying information"  as "dialing or signaling information that identifies the origin,  direction, destination, or termination of each communication  generated or received by a subscriber by means of any  equipment, facility, or service of a telecommunications carrier."  Id. § 1001(2).  CALEA requires each carrier to


5
ensure that its equipment, facilities, or services ... are capable of


6
(1) expeditiously isolating and enabling the government, pursuant to a court order or other lawful authorization, to intercept, to the exclusion of any other communications, all wire and electronic communications carried by the carrier within a service area to or from equipment, facilities, or services of a subscriber of such carrier concurrently with their transmission to or from the sub-scriber's equipment, facility, or service, or at such later time as may be acceptable to the government;  [and]


7
(2) expeditiously isolating and enabling the government, pursuant to a court order or other lawful authorization, to access call-identifying information that is reasonably available to the carrier....


8
Id. § 1002(a)(1)-(2).  Carriers must also "facilitat[e] authorized communications interceptions and access to call identifying information ... in a manner that protects ... the  privacy and security of communications and call-identifying  information not authorized to be intercepted."  Id.  § 1002(a)(4)(A).  Because Congress intended CALEA to  "preserve the status quo," the Act does not alter the existing  legal framework for obtaining wiretap and pen register authorization, "provid[ing] law enforcement no more and no less  access to information than it had in the past."  H.R. Rep. No.  103-827, pt. 1, at 22.  CALEA does not cover "information services" such as e-mail and internet access.  47 U.S.C.  §§ 1001(8)(C)(i), 1002(b)(2)(A).


9
To ensure efficient and uniform implementation of the Act's  surveillance assistance requirements without stifling technological innovation, CALEA permits the telecommunications  industry, in consultation with law enforcement agencies, regulators, and consumers, to develop its own technical standards  for meeting the required surveillance capabilities.  See id.  § 1006.  The Act "does not authorize any law enforcement  agency or officer" to dictate the specific design of communications equipment, services, or features.  Id. § 1002(b)(1).  Although carriers failing to meet CALEA's requirements may  incur civil fines of up to $10,000 a day, see 18 U.S.C.  § 2522(c), the Act establishes a safe harbor under which  carriers that comply with the accepted industry standards will  be deemed in compliance with the statute, see 47 U.S.C.  § 1006(a)(2).  But "if a Government agency or any other  person believes that such requirements or standards are  deficient, the agency or person may petition the Commission  to establish, by rule, technical requirements or standards...."  Id. § 1006(b).  Such Commission rules must:


10
(1) meet the assistance capability requirements of section 1002 of [the statute] by cost-effective methods;


11
(2) protect the privacy and security of communications not authorized to be intercepted;


12
(3) minimize the cost of such compliance on residential ratepayers;


13
(4) serve the policy of the United States to encourage the provision of new technologies and services to the public;  and


14
(5) provide a reasonable time and conditions for compliance with and the transition to any new standard, including defining the obligations of telecommunications carriers under section 1002 of [the statute] during any transition period.


15
Id.


16
Following two years of proceedings and extensive negotiations with the FBI, the Telecommunications Industry Association ("TIA"), an accredited standard-setting body, adopted  technical standards pursuant to CALEA's safe harbor, publishing them as Interim Standard/Trial Use Standard J-STD025.  Known as the "J-Standard," this document outlines the  technical features, specifications, and protocols for carriers to  make subscriber communications and call-identifying information available to law enforcement agencies having appropriate  legal authorization.


17
Challenging the J-Standard as "deficient," id., the Center  for Democracy and Technology petitioned the Commission for  a rulemaking to remove two provisions it claimed not only  violate CALEA's privacy protections but also impermissibly  expand government surveillance capabilities beyond those  authorized by the statute.  One of the challenged J-Standard  provisions requires carriers to make available to law enforcement agencies the physical location of the nearest antenna  tower through which a cellular telephone communicates at the  beginning and end of a call.  According to the Center, this  requirement effectively converts ordinary mobile telephones  into personal location-tracking devices, giving law enforcement agencies access to far more information than theypreviously had.  The Center also argued that cellular antenna  location information is not "call-identifying information," as  defined in both the statute and the J-Standard.  The other  challenged provision relates to what is known as "packet mode data," which we shall describe in detail later in this  opinion.  See Section III infra.  At this point, suffice it to say  that, according to the Center, the J-Standard's inclusion of  packet-mode data enables law enforcement agencies to obtain  call content with no more than a pen register order.


18
Both the Justice Department and the FBI also petitioned  the Commission to modify the J-Standard, arguing that it  does not include all of CALEA's required assistance capabilities.  The Department provided a list, known as the "FBI  punch list," of nine additional surveillance capabilities that  law enforcement wanted the Commission to add.  The punch  list included telephone numbers of calls completed using calling cards as well as signaling information related to  custom calling features such as call waiting and conference  calling.


19
After soliciting public comment on the petitions, see Public  Notice, 13 F.C.C.R. 13786 (1998);  Further Notice of Proposed Rule making 13 F.C.C.R. 22632 (1998), the Commission  resolved the challenges to the J-Standard in its Third Report  & Order, see In the Matter of Communications Assistance  for Law Enforcement Act, 14 F.C.C.R. 16794 (1999) ("Third  Report & Order").  The Commission denied the Center's  petition to delete cellular antenna location information and  packet-mode data.  The location of cellular antenna towers  used at the beginning and end of wireless calls, the Commission ruled, falls within CALEA's definition of call-identifying  information because it "identifies the 'origin' or 'destination'  of a communication."  Id. at 16815 p 44.  With respect to  packet-mode data, the Commission recognized the uncertainty regarding the technical feasibility of separating call content  (requiring a Title III wiretap warrant) from call-identifying  information (requiring only a pen register order).  See id. at  16819-20 pp 55-56.  Although inviting further study of the  matter, the Commission declined to remove packet-mode data  from the J-Standard, explaining that CALEA makes no  distinction between packet-mode and other communications  technologies.  See id.


20
The Commission granted the Justice Department/FBI petition in part, adding four of the nine punch list capabilities to  the J-Standard, adding two more in part (neither is challenged here), and declining to add three others (also unchallenged).  See id. at 16852 p 138.  The four additions are:


21
(1) "Post-cut-through dialed digit extraction":  This re-quires carriers to use tone-detection equipment to generate a list of all digits dialed after a call has been connected.  Such digits include not only the telephone numbers dialed after connecting to a dial-up long-distance carrier (e.g., 1-800-CALL-ATT), but also, for example, credit card or bank account numbers dialed in order to check balances or transact business using auto-mated telephone services, see id. at 16842-46 pp 112-23;


22
(2) "Party hold/join/drop information":  This includes telephone numbers of all parties to a conference call as well as signals indicating when parties are joined to the call, put on hold, or disconnected, see id. at 16825-28pp 68-75;


23
(3) "Subject-initiated dialing and signaling information":  This includes signals generated by activating features such as call forwarding and call waiting, see id. at16828-30 pp 76-82;  and


24
(4) "In-band and out-of-band signaling":  This includes information about signals sent from the carrier's network to a subject's telephone, such as message-waiting indicators, special dial tones, and busy signals, see id. at 16830-33 pp 83-89.


25
Two industry associations--the United States Telecom Association and the CellularTelecommunications Industry Association--joined by the Center for Democracy and Technology,  filed a petition for review in this court, as did the Electronic  Frontier Foundation, Electronic Privacy Information Center,  and American Civil Liberties Union.  All petitions were consolidated.  The Telecommunications Industry Association, the  standard-setting organization that developed and issued the  J-Standard, joined by another trade group, the Personal  Communications Industry Association, and two telecommunications carriers, Sprint PCS and U S West, intervened to  challenge the Third Report & Order, focusing on dialed digit  extraction, the most costly of the added punch list items. The FCC and the Justice Department filed separate briefs  defending the Commission's action.


26
The consolidated petitions for review challenge six capabilities:  antenna tower location information and packet-mode  data, both of which were included in the J-Standard;  and  dialed digit extraction, party hold/join/drop, subject-initiated  dialing and signaling, and in-band and out-of-band signaling,  the four punch list capabilities added by the Commission. With respect to these challenged capabilities, petitioners contend that the Commission:  (1) exceeded its authority under  CALEA because at least some of the information required to be made available to law enforcement is neither call content  nor "call-identifying information that is reasonably available  to the carrier," 47 U.S.C. § 1002(a)(2);  (2) failed adequately  to "protect the privacy and security of communications not  authorized to be intercepted," as required by the statute, id.  § 1006(b)(2);  and (3) failed both to ensure that the capability  requirements are implemented "by cost-effective methods,"  id. § 1006(b)(1), and to "minimize the cost of such compliance  on residential ratepayers," id. § 1006(b)(3).  In Section II, we  take up the four challenged punch list capabilities and antenna tower location information.  We consider packet-mode  communications in Section III.

II

27
Whether CALEA requires carriers to make available antenna tower location information and the four punch list  capabilities turns on what the Act means by "call-identifying  information."  To repeat, section 102(2) of CALEA defines  "call-identifying information" as "dialing or signaling information that identifies the origin, direction, destination, or termination of each communication generated or received by a  subscriber by means of any equipment, facility, or service of a  telecommunications carrier."  Id. § 1001(2).  The Commission interprets this definition to require adoption of all challenged capabilities, each of which, it claims, makes available  information identifying the "origin, direction, destination, or  termination" of calls.  Petitioners argue that the definition  limits "call-identifying information" to telephone numbers. Because location information and the four punch list items  require carriers to make available more than telephone numbers, petitioners contend that these capabilities exceed  CALEA's requirements.  They argue that there is no statutory basis for location information to have been included in the  J-Standard or for the Commission to have mandated the  punch list capabilities.


28
To resolve this challenge to the Commission's interpretation of a statute it is charged with administering, we proceed  according to Chevron U.S.A. Inc. v. Natural Resources Defense Council, Inc., 467 U.S. 837 (1984).  We ask first "whether Congress has directly spoken to the precise question at  issue."  Id. at 842.  If it has, "that is the end of the matter; for the court, as well as the agency, must give effect to the  unambiguously expressed intent of Congress."  Id. at 842-43.If we find the statute silent or ambiguous with respect to the  precise question at issue, we proceed to the second step of  Chevron analysis, asking "whether the agency's answer is  based on a permissible construction of the statute."  Id. at  843.  At this stage of Chevron analysis, we afford substantial  deference to the agency's interpretation of statutory language.  See id. at 844.


29
Beginning with Chevron step one, we think it clear that  section 102(2) does not "unambiguously" answer "the precise  question at issue":  Is "call-identifying information" limited to  telephone numbers?  To begin with, had Congress intended  to so limit "call-identifying information," it could have done so  expressly by using the term "telephone number" as it did in  both sections 103(a)(2) and 207(a)(1)(C) of CALEA.  See 47  U.S.C. § 1002(a)(2);  18 U.S.C. § 2703(c)(1)(C).  "Where Congress includes particular language in one section of a statute  but omits it in another section of the same Act, it is generally  presumed that Congress acts intentionally and purposely in  the disparate inclusion or exclusion."  Russello v. United  States, 464 U.S. 16, 23 (1983) (internal quotation marks and  alteration omitted);  see also, e.g., District of Columbia Hosp.  Ass'n v. District of Columbia, 2000 WL 946581, at *3 (D.C.  Cir.).  CALEA's definition of "call-identifying information,"  moreover, refers not just to "dialing ... information," but  also to "signaling information," leading us to believe that  Congress may well have intended the definition to cover  something more than just the "dialing ... information" conveyed by telephone numbers.  Finally, section 103(a)(2) of  CALEA provides that when information is sought pursuant to  a pen register or trap and trace order, "call-identifying  information shall not include any information that may disclose the physical location of the subscriber (except to the  extent that the location may be determined from the telephone number)."  47 U.S.C. § 1002(a)(2).  As the Commission observed, Congress would have had no need to add this  limitation if "call-identifying information" referred only to telephone numbers.  See Third Report & Order, 14 F.C.C.R.  at 16815 p 44 n.95.


30
In support of their argument that "call-identifying information" unambiguously means only telephone numbers, petitioners call our attention to the House Judiciary Committee  Report, which does seem to describe such information in  terms of telephone numbers.  See H.R. Rep. No. 103-827, pt.  1, at 21.  Apparently addressing post-cut-through dialed digits, the Report even says that "other dialing tones that may  be generated by the sender that are used to signal customer  premises equipment of the recipient are not to be treated as  call-identifying information."  Id.  Yet the Report also echos  CALEA's inherent ambiguity, stating that call-identifying  information is "typically the electronic pulses, audio tones, or  signalling messages that identify the numbers dialed or otherwise transmitted for the purpose of routing calls through the  telecommunications carrier's network."  Id. (emphasis added).  Although another section of the Report describes  CALEA as requiring carriers to make available "information  identifying the originating and destination numbers of targeted communications, but not the physical location of targets,"  id. at 16, that passage, as the Commission points out, appears  to deal with an earlier version of the statute--before the  definition of "call-identifying information" was expanded by  adding the terms "direction" and "termination."


31
Petitioners next argue that limiting "call-identifying information" to telephone numbers mirrors ECPA's definitions of  "pen register" and "trap and trace device."  Pen registers  record "the numbers dialed or otherwise transmitted," 18  U.S.C. § 3127(3) (emphasis added), and trap and trace devices record "the originating number of ... an electronic  communication," id. § 3127(4) (emphasis added).  Petitioners  contend that because CALEA's enforcement provisions are  limited to intercept warrants and to pen register and trap and  trace device orders, the statute's required capabilities must  likewise be restricted to the call content intercepted in a  wiretap and the dialed telephone numbers recorded by pen  registers.  "It would have made no sense," say petitioners,  "for Congress to require carriers to provide a capability that  the surveillance laws do not authorize the government to  use."  Final Brief of Petitioners USTA, CTIA, and CDT at  16.


32
This is an interesting argument, but hardly sufficient to  resolve CALEA's ambiguity.  CALEA neither cross references nor incorporates ECPA's definitions of pen registers and trap and trace devices.  Moreover, the fact that  CALEA's definition of "call-identifying information" differs  from ECPA's description of the information obtainable by pen  registers and trap and trace devices reinforces the statute's  inherent ambiguity.


33
Petitioners also rely on the J-Standard's explanation of the  terms used in CALEA's definition of call-identifying information, pointing out that the J-Standard limits these terms to  telephone numbers:


34
[D]estination is the number of the party to which a call is being made (e.g., called party);  direction is the number to which a call is re-directed or the number from which it came, either incoming or outgoing (e.g., redirected-to party or redirected-from party);  origin is the number of the party initiating a call (e.g., calling party);  and termination is the number of the party ultimately receiving a call (e.g., answering party).  Interim Standard/Trial Use Standard J-STD-025, at 5.


35
Because cell phone location information and the four challenged punch list capabilities call for more than telephone  numbers, petitioners argue that they conflict with the  J-Standard's interpretation of CALEA.  Again, this is an  interesting argument, but not relevant at Chevron step one,  where our focus is on whether "the intent of Congress is  clear."  Chevron, 467 U.S. at 842 (emphasis added).  On that  issue, the authors of the J-Standard can provide no guidance.


36
Finally, petitioners point out that in Smith v. Maryland the  Supreme Court held that although the Fourth Amendment  protects the privacy of information conveyed during telephone  calls, i.e., the contents of conversations, callers have no reasonable expectation of privacy in dialed telephone numbers. See 422 U.S. at 742-45.  Reading Smith's exception narrowly,  petitioners argue that other than call content interceptable  under a wiretap order, CALEA cannot require carriers to  provide law enforcement agencies anything more than the  telephone numbers dialed in order to complete calls.  But  petitioners point to nothing in either CALEA or its legislative history to suggest that Congress meant to follow Smith's  protected-unprotected distinction in defining call-identifying  information.  Moreover, Smith's reason for finding no legitimate expectation of privacy in dialed telephone numbers-that callers voluntarily convey this information to the phone  company in order to complete calls--applies as well to much  of the information provided by the challenged capabilities. See id. at 742.


37
Turning to the government's position, we understand neither the Commission nor the Justice Department to be arguing that section 102(2) unambiguously includes more than  telephone numbers in the definition of "call-identifying information," and for good reason.  Although we reject petitioners' argument that section 102(2) is unambiguously limited to  telephone numbers, we think it equally clear that nothing  points to an "unambiguously expressed intent of Congress" to  require every one of the challenged assistance capabilities. Chevron, 467 U.S. at 843.  Instead, the two agencies urge us  to defer to the Commission's interpretation of the statute  pursuant to Chevron's second step.  See id. at 844.  According to the agencies, the Commission reasonably interpreted  "call-identifying information" to include the punch list capabilities and antenna tower location information. Because we  reach different conclusions with respect to the punch list and  location information, we discuss them separately.

Punch List

38
Responding to the government's Chevron-two argument,  petitioners contend:  (1) the Commission's interpretation of  "call-identifying information" to include the four added punch  list capabilities is unreasonable and thus unworthy of  Chevron-two deference;  and (2) the Commission's decision to  modify the J-Standard to include the punch list reflects a lack  of reasoned decision making, see generally, Motor Vehicle  Mfrs Ass'n v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29  (1983).  Because we agree with the latter argument, we need  not address the Commission's plea for Chevron deference.


39
It is well-established that " 'an agency must cogently explain why it has exercised its discretion in a given manner'  and that explanation must be 'sufficient to enable us to  conclude that the [agency's action] was the product of reasoned decision making.' "  A.L.  Pharma, Inc. v. Shalala, 62  F.3d 1484, 1491 (D.C. Cir. 1995) (internal citation omitted)  (quoting Motor Vehicle Mfrs., 463 U.S. at 48, 52).  The  Commission's determination that CALEA requires carriers to  implement the four punch list items fails this test.  The  Commission asserted that each of the challenged punch list  capabilities is required by CALEA because each requires  carriers to make available "call-identifying information," but  it never explained--not in the Order and not in its brief--the  basis for this conclusion.  Nowhere in the record did the  Commission explain how the key statutory terms--origin,  direction, destination, and termination--can cover the wide  variety of information required by the punch list.  For example, the Commission uses "origin" of a communication to  mean not only the telephone number of an incoming call, but  also a tone indicating that a new call is waiting.  Adding the  waiting call to create a three-way call is yet another origin. If a party is placed on hold and then re-joined to the call, the  Commission describes that event as "the temporary origin  ... of a communication."  Third Report & Order, 14 F.C.C.R.  at 16827 p 74.  The Commission similarly uses "termination"  to cover many different kinds of information including telephone numbers of outgoing calls, signals indicating that calls  have been placed on hold or switched to waiting calls, signals  that parties have been dropped from conference calls, busy  signals, and ringing tones.  Yet the Commission never explained how each of these bits of information "identifies the  ... termination of each communication."  47 U.S.C.  § 1001(2) (emphasis added).  Instead, it simply concluded,  with neither analysis nor explanation, that each capability is  required by CALEA.  See, e.g., Third Report & Order, 14  F.C.C.R. at 16827 p 74 ("Party join information appears to  identify the origin of a communication;  party drop, the  termination of a communication;  and party hold, the temporary origin, temporary termination, or re-direction of a communication." (emphasis added)).


40
Perhaps the Commission can satisfactorily explain how  CALEA's terms can encompass such a wide range of information.  Because it has not, we cannot tell whether the punch  list capability requirements are "the product of reasoned  decision making."  Motor Vehicle Mfrs., 463 U.S. at 52.


41
The Commission's failure to explain its reasoning is particularly serious in view of CALEA's unique structure.  Rather  than simply delegating power to implement the Act to the  Commission, Congress gave the telecommunications industry  the first crack at developing standards, authorizing the Commission to alter those standards only if it found them "deficient."  47 U.S.C. § 1006(b).  Although the Commission used  its rule making power to alter the J-Standard, it identified no  deficiencies inthe Standard's definitions of the terms "origin," "destination," "direction," and "termination," which describe "call-identifying information" in terms of telephone  numbers.  Were we to allow the Commission to modify the  J-Standard without first identifying its deficiencies, we would  weaken the major role Congress obviously expected industry  to play in formulating CALEA standards.


42
The Commission's decision to include the four challenged  punch list capabilities suffers from two additional defects. The first relates to CALEA's requirements that Commission  rules must "meet the assistance capability requirements of  section 1002 of this title by cost-effective methods" and  "minimize the cost of such compliance on residential ratepayers."  Id. § 1006(b)(1), (3).  Faced with multiple cost estimates ranging as high as $4 billion for all carriers to implement the core J-Standard capabilities, the Commission  adopted an estimate submitted by five software suppliers  predicting that they would earn $916 million in revenues for  implementing the core J-Standard and $414 million for implementing the punch list.  Third Report & Order, 14 F.C.C.R.  at 16805 p 20, 16809 p 30.  The Commission acknowledged  that "these estimates ... do not represent all carrier costs of  implementing CALEA," id. at 16809 p 30, yet it found them to be "a reasonable guide of the costs to wire line, cellular, and  broadband PCS carriers for CALEA compliance," id.


43
The Commission never explained how its Order would  satisfy CALEA's requirements "by cost-effective methods."47 U.S.C. § 1006(b)(1).  It made no attempt to compare the  cost of implementing the punch list capabilities with the cost  of obtaining the same information through alternative means,  nor did it explain how it measured cost-effectiveness.  Although it mentioned residential ratepayers, it never explained  what impact its Order would have on residential telephone  rates.  Instead, pointing out that the telecommunications  industry, by ratifying the J-Standard, had agreed to its  implementation cost, the Commission compared the additional  cost of each punch list capability with the total cost of the  J-Standard and then concluded that each additional cost was  "not so exorbitant as to require automatic exclusion of the  capability."  Third Report & Order, 14 F.C.C.R. at 16824  p 66, 16828 p 75, 16829-30 p 82, 16832 p 89.  But why?  The  Commission failed to explain how it decided that implementing the punch list capabilities, which increase J-Standard  costs by more than 45 percent (even by the Commission's  conservative estimates) is "not so exorbitant."  Suppose  punch list costs had exceeded J-Standard costs by 90 percent. Would that have been too "exorbitant"?  Asked this question  at oral argument, Commission counsel told us only, "I suppose it is a line-drawing exercise."


44
The Commission's response to CALEA's cost directives  reflects a classic case of arbitrary and capricious agency  action.  Fundamental principles of administrative law require  that agency action be "based on a consideration of the relevant factors," Citizens to Preserve Overton Park, Inc. v.  Volpe, 401 U.S. 402, 416 (1971), and rest on reasoned decision making in which "the agency must examine the relevant data  and articulate a satisfactory explanation for its action including a rational connection between the facts found and the  choice made," Motor Vehicle Mfrs., 463 U.S. at 43 (internal  quotation marks omitted).  Of course, we do not require  "ideal clarity";  we will "uphold a decision ... if the agency's  path may reasonably be discerned."  Bowman Transp., Inc. v. Arkansas-Best Freight System Inc., 419 U.S. 281, 286  (1974).  On the record before us, however, we cannot "discern" how the Commission interpreted "cost-effective," nor  why it considered the substantial costs of the punch list  capabilities to be "not so exorbitant," nor finally what impact  it thought the Order would have on residentialratepayers. Missing, in other words, is "a rational connection between the  facts found and the choice made."  Motor Vehicle Mfrs., 463  U.S. at 43.


45
The second defect in the Order relates to the Commission's  failure to comply with CALEA's requirement that it "protect  the privacy and security of communications not authorized to  be intercepted," 47 U.S.C. § 1006(b)(2), with respect to post cut-through dialed digit extraction.  This punch list capability  requires carriers to electronically monitor the communications channel that carries audible call content in order to  decode all digits dialed after calls are connected or "cut  through."  Some post-cut-through dialed digits are telephone  numbers, such as when a subject places a calling card, credit  card, or collect call by first dialing a long-distance carrier  access number and then, after the initial call is "cut through,"  dialing the telephone number of the destination party.  Post cut-through dialed digits can also represent call content.  For  example, subjects calling automated banking services enter  account numbers.  When calling voice-mail systems, they enter passwords.  When calling pagers, they dial digits that  convey actual messages.  And when calling pharmacies to  renew prescriptions, they enter prescription numbers.


46
The government contends that a law enforcement agency  may receive all post-cut-through digits with a pen register  order, subject to CALEA's requirement that the agency uses  "technology reasonably available to it" to avoid processing  digits that are content.  18 U.S.C. § 3121(c).  No court has  yet considered that contention, however, and it may be that a  Title III warrant is required to receive all post-cut-through  digits.  The Commission therefore had a statutory obligation  to address how its Order, which requires the capability to  provide all dialed digits pursuant to a pen register order,  would "protect the privacy and security of communications  not authorized to be intercepted."  47 U.S.C. § 1006(b)(2).


47
The Commission spoke of law enforcement's need to obtain  post-cut-through dialed digits and of the cost of providing  them, but it never explained, as CALEA requires, how its  rule will "protect the privacy and security of communications  not authorized to be intercepted."


48
Several commenters, moreover, suggested ways in which  law enforcement agencies having only pen register orders  could obtain post-cut-through phone numbers while protecting the privacy of call content.  The Commission rejected  these alternatives, claiming not that they are technologically  infeasible, but that they "would shift the cost burden from the  originating carrier to the LEA," "could be time-consuming,"  and might burden law enforcement's ability "to conduct electronic surveillance effectively and efficiently."  Third Report  & Order, 14 F.C.C.R. at 16845 p 121.  This is an entirely  unsatisfactory response to CALEA's privacy provisions.  The  statute requires the Commission to consider more than the  burden on law enforcement--after all, any privacy protections  burden law enforcement to some extent.  The Commission's  rules must not only meet CALEA's "assistance capability  requirements," 47 U.S.C. § 1006(b)(1), but also "protect the  privacy and security of communications not authorized to be  intercepted," id. § 1006(b)(2).


49
The absence of any meaningful consideration of privacy  with respect to dialed digit extraction does not seem to stem  from a failure on the Commission's part to understand the  privacy consequences of its Order.  To the contrary, recognizing that there is no way to distinguish between digits dialed  to route calls and those dialed to communicate information,  the Commission expressed "concern[ ] about ... the privacy  implications of permitting LEAs to access non-call-identifying  digits (such as bank account numbers) with only a pen  register warrant."  Third Report & Order, 14 F.C.C.R. at  16846 p 123.  Yet the Order requires carriers to make available all post-cut-through dialed digits--those that convey  content as well as telephone numbers.


50
Asked at oral argument to point out how the Commission  applied CALEA's privacy mandate to post-cut-through dialed digits, Commission counsel stated, "we addressed ourselves to  the privacy questions with a little bit of hand wringing and  worrying...."  Transcript of Oral Argument at 29.  Neither  hand wringing nor worrying can substitute for reasoned  decision making.


51
For the foregoing reasons, we vacate the portions of the  Commission's Order dealing with the four challenged punch  list capabilities and remand for further proceedings consistent  with this opinion.

Location Information

52
We reach a different conclusion with respect to the Commission's refusal to remove the antenna tower location information capability from the J-Standard.  This provision requires carriers to make available the physical location of the  antenna tower that a mobile phone uses to connect at the  beginning and end of a call.  Unlike the Commission's adoption of the punch list, its decision with regard to location  information is both reasoned and reasonable.


53
To begin with, as the Commission observed in the Third  Report & Order, defining "call-identifying information" to  include antenna tower location finds support in  CALEA's text.  In particular, section 103(a)(2) provides that  "with regard to information acquired solely pursuant to the  authority for pen registers and trap and trace devices ...  call-identifying information shall not include any information  that may disclose the physical location of the subscriber  (except to the extent that the location may be determined  from the telephone number)."  47 U.S.C. § 1002(a)(2).  As we  note above, the Commission read this provision to imply that  location information falls within the definition of call identifying information.  Section 103(a)(2), the Commission  ruled, "simply imposes upon law enforcement an authorization  requirement different from that minimally necessary for use  of pen registers and trap and trace devices."  Third Report &  Order, 14 F.C.C.R. at 16815 p 44.  Disagreeing, petitioners  argue that section 103(a)(2) narrows the definition of call identifying information and should not be read as an affirmative grant of authority for law enforcement agencies to obtain location information.  As the Commission explained, however,  if "call-identifying information" did not include location information, this provision would have no function.  See id. at  16815 p 44 & n.95.  In reaching this conclusion, the Commission was simply following the well-accepted principle of statutory construction that requires every provision of a statute to  be given effect.  See Washington Market Co. v. Hoffman, 101  U.S. 112, 115-16 (1879) ("We are not at liberty to construe  any statute so as to deny effect to any part of its language.").


54
The Commission's approach to location information also  finds support in CALEA's use of the word "signaling" in the  definition of "call-identifying information."  As the agency  explains in its brief, a mobile phone "sends signals to the  nearest cell site at the start and end of a call.  These signals,  which are necessary to achieve communications between the  caller and the party he or she is calling, clearly are 'signaling  information.'  Information about the cell sites associated with  mobile calls therefore falls squarely within the statutory  definition of call-identifying information."  Brief for Federal  Communications Commission at 38.


55
Not only did the Commission elucidate the textual basis for  interpreting "call-identifying information" to include location  information, but it also explained how that result comports  with CALEA's goal of preserving the same surveillance capabilities that law enforcement agencies had in POTS (plain old  telephone service).  "[I]n the wireline environment," the  Commissionexplained, law enforcement agencies "have generally been able to obtain location information routinely from  the telephone number because the telephone number usually  corresponds with location."  Third Report & Order, 14  F.C.C.R. at 16816 p 45.  In the wireless environment, "the  equivalent location information" is "the location of the cell  sites to which the mobile terminal or handset is connected at  the beginning and at the termination of the call."  Id.  Accordingly, the Commission concluded, "[p]rovision of this  particular location information does not appear to expand or  diminish law enforcement's surveillance authority under prior  law applicable to the wireline environment."  Id.


56
The Commission's refusal to remove location information  from the J-Standard, moreover, does not share the other  problems that led us to vacate the punch list portion of the  Third Report & Order.  As to cost, location information was  included in the J-Standard adopted by industry, so it is  unaffected by the deficiencies in the Commission's cost analysis.  And in contrast to dialed digit extraction, the Commission's analysis of the location capability did more than just  pay lip service to CALEA's privacy requirements.  Most  important, the Commission demonstrated its understanding  that antenna location information could only be obtained with  something more than a pen register order, see id. at 16815  p 44, a point the Justice Department concedes in its brief:  "A  pen register order does not by itself provide law enforcement  with authority to obtain location information, and we have  never contended otherwise."  Final Brief for the United  States at 19.  Expressly relying on CALEA's privacy protection provisions, moreover, the Commission rejected a New  York Police Department proposal that would have required  triangulating signals from multiple cellular antenna towers to  pinpoint a wireless phone's precise location throughout a call's  duration.  See Third Report & Order, 14 F.C.C.R. at 16816  p 46.  "[S]uch a capability," the Commission found, "poses  difficulties that could undermine individual privacy."  Id.


57
For these reasons, we deny the petitions for review with  respect to location information.

III

58
This brings us to petitioners' challenge to the Commission's  decision not to remove the packet-mode data requirement  from the J-Standard.  In conventional circuit-mode telecommunications, a single circuit is opened between caller and  recipient and all electronic signals that make up the communication travel along the circuit.  In digital packet-switched  networks, communications do not travel along a single path. Instead, a call is broken into a number of discrete digital data  packets, each traveling independently through the network  along different routes.  Data packets are then reassembled in  the proper sequence at the call's destination.  Like an envelope, each digital packet has two components:  it contains a  portion of the communication message, and it bears an address to ensure that it finds its way to the correct destination  and is reassembled in proper sequence.  The address information appears in the packet's "header."  The message within the packet is known as the "body" or "payload."  The  J-Standard requires that carriers make available both header  and payload.


59
Telecommunication carrier petitioners claim that packet  headers (call-identifying information) cannot be separated  from packet bodies or payloads (call content).  Accordingly,  they and the privacy petitioners argue that any packet-mode  data provided to a law enforcement agency pursuant to a pen  register order will inevitably include some call content, thus  violating CALEA's privacy protections.  The FBI disagrees."[A]s a technical matter," it argued before the Commission,  "it is perfectly feasible for a LEA to employ equipment that  distinguishes between a packet's header and its communications payload and makes only the relevant header informationavailable for recording or decoding."  Third Report & Order,  14 F.C.C.R. at 16818 p 54.


60
The Commission considered these conflicting views about  the feasibility of separating call content from packet header  data, concluding that "the record is not sufficiently developed  to support any particular technical requirements for packetmode communications."  Id. at 16817 p 48.  At the same time,  the Commission acknowledged that "privacy concerns could  be implicated if carriers were to give to LEAs packets  containing both call-identifying and call content information  when only the former was authorized."  Id. Stating that  "further efforts can be made to find ways to better protect  privacy by providing law enforcement only with the information to which it is lawfully entitled," the Commission asked  the Telecommunications Industry Association, which developed the J-Standard, "to study CALEA solutions for packet mode technology and report to the Commission in one year  on steps that can be taken, including particular amendments  to [the J-Standard], that will better address privacy concerns."  Id. at 16819 p 55.  In the meantime, however, finding  the record insufficient to warrant modification of the J-Standard's packet-mode data provision, the Commission  directed that it be implemented "no later than September 30,  2001."  Id.  "That date," the Commission explained, "is 15  months after the June 30, 2000 CALEA compliance deadline,  and will afford manufacturers that have not yet developed a  packet-mode capability the time needed to do so."  Id.  At  the same time, the Commission emphasized that it viewed this  as an interim solution.  "We recognize that, in view of the  growing importance of packet-mode communications, a timely  permanent solution is essential.  Accordingly, we expect that  TIA will deliver a report to us no later than September 30,  2000 that will detail a permanent solution...."  Id. at 16820  p 56.


61
The Commission's denial of the petitions to remove packet mode data from the J-Standard suffers from none of the  shortcomings that undermined its handling of the punch list  capabilities.  First, because nobody questions that packet  header information contains "call-identifying information," the  ambiguity of that term's definition does not affect the packet mode requirement.  Second, as with location information, but  unlike the four punch list capabilities, because the packet mode requirement was included in the J-Standard adopted  by industry it is unaffected by the deficiencies in the Commission's cost analysis.  Third, unlike the case of dialed digit  extraction, the Commission thoroughly considered the privacy  implications of packet-mode data and invited further study to  "better address privacy concerns."  Id. at 16819 p 55.


62
Finally, nothing in the Commission's treatment of packet mode data requires carriers to turn over call content to law  enforcement agencies absent lawful authorization.  Although  the Commission appears to have interpreted the J-Standard  as expanding the authority of law enforcement agencies to  obtain the contents of communications, see id., the Commission was simply mistaken.  All of CALEA's required capabilities are expressly premised on the condition that any information will be obtained "pursuant to a court order or other  lawful authorization."  47 U.S.C.  § 1002(a)(1)-(3).  CALEA  authorizes neither the Commission nor the telecommunications industry to modify either the evidentiary standards or procedural safeguards for securing legal authorization to obtain packets from which call content has not been stripped,  nor may the Commission require carriers to provide the  government with information that is "not authorized to be  intercepted."  Id.  See also Final Brief for the United States  at 4 ("If the government lacks the requisite legal authority to  obtain particular information, nothing in Section 103 obligates  a carrier to provide such information.").  Petitioners thus  have no reason to fearthat "compliance with the Order will  force carriers to violate their duty under CALEA to 'protect  the privacy and security of communications ... not authorized to be intercepted.' "  Final Brief of Petitioners USTA,  CTIA, and CDT at 35.  We therefore deny the petition for  review with respect to packet-mode data.

IV

63
We grant the petitions for review in part, vacate the  provisions of the Third Report & Order dealing with the four  challenged punch list capabilities, and remand to the Commission for further proceedings consistent with this opinion.  In  all other respects, we deny the petitions for review.


64
So ordered.

