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• Information regarding the intercept subject's line 2
Line Information for Terminating Calls. Law enforcement agencies require access to call setup information for all completed and attempted calls to the intercept subject. In this case, call setup information refers to information on both the subject's and the calling party's line. Access to information about the subject's line is required for all calls terminating to the intercept subject. Access to information about the calling party's line is required when it is delivered to the service provider supporting the called intercept subject's communications. The type of line information available for both parties depends on the communications services in use by the calling party and the intercept subject. Exhibit 3–1 lists a number of examples.
Plain Old Telephone
• Associated Directory Number
provider switch to identify the
calling party (if available)
(MIN) • Personal Number/Directory
Terminal Equipment Identifier • Directory Number • Other available items, for
example, Automatic Numbering Identification (ANI)
Associated Directory Number • Line Equipment Identifier • Call Type/Bearer Capability • Service Profile Identifier (SPID) • Numbers used by the service
provider switch to identify the
Directory Number of the PBX
called party (if available)
example, Automatic Numbering Identification (ANI)
Line Information for Originating Calls. When the intercept subject originates a call, law enforcement requires access to information about the communications line used by the subject. The information available to describe a subject's line varies based on the type of communications service used by the intercept subject. Types of line identifiers include directory numbers (DN), mobile identification numbers (MIN), and personal numbers. Exhibit 3-2 presents several examples of information needed about the subjects line and required by law enforcement agencies when the intercept subject originates a call.
2 The term "line" is used broadly to refer to the transmission path from a subscriber terminal to the network. This transmission path may be via a wireline or wireless medium (for example, copper wire, radio link).
INFORMATION ABOUT THE SUBJECT'S LINE WHEN THE SUBJECT ORIGINATES CALLS
Dialing and Signaling Information. In addition to the subject's line information, law enforcement agencies require access to the dialing the signaling information generated by the subject for all calls originated by the intercept subject. Examples of dialing and signaling information include the following: • All digits dialed by the subject and any signaling information used to establish
or direct call flow • Subsequent dialing information generated by the subject after cut-through • The terminating number of the destination derived by the originating switch
based on its interpretation of the subject's dialed digits or other call direction commands. Redirection Numbers. Access to call setup information also includes redirection numbers when calls are forwarded or transferred using custom calling features. Law enforcement requires access to the forwarded-to number when the intercept subject transfers or forwards calls to another number. For a call terminating to the intercept subject, law enforcement agencies require access to any available redirection numbers when multiple forwards or transfers are involved in the call attempt. As an example, a call initiated by a calling party may be forwarded or transferred several times before reaching the intercept subject. Law enforcement requires the number of the calling party that originated the call, as well as any available intermedi. ate numbers used to redirect the call. Exhibit 3-3 illustrates several all redirection scenarios.
Call Attempt Alerts. Law enforcement agencies require notification of all call attempts placed to or by the intercept subject. For example, in the case of a wireline intercept on a local loop, law enforcement generates a time stamp after detecting the local exchange carrier's (LEC) signaling for on-hook, ringing, and off-hook. However, local exchange carrier signaling protocols may change with emerging technologies. In future implementations, out-of-band signaling using signaling transfer points (STP) may replace in-band protocols currently used by law enforcement to detect call activity. Therefore, law enforcement agencies require some form of notification to provide a trigger for monitoring equipment.
CALL CONTENT Law enforcement agencies require access to call content for all calls originating from and terminating to the intercept subject's fixed or mobile number, terminal equipment, or other identifier. Access to call content is required regardless of the type of communications used in the call including cases when the communications between the intercept subject and other parties are sent and received over separate channels. The communications between the intercept subject and other parties may take place using wireline systems, wireless (mobile) systems, or a combination.
Service Arrangements. In a wireline-to-wireline call, both the calling and called parties use traditional wireline services. Examples of wireline services include coin, Plain Old Telephone Service (POTS), and Integrated Services Digital Network (ISDN). In a wireline-to-mobile or mobile-to-wireline call, one party uses a mobile communications service while the second party uses a wireline service. With mobile communications services, the service subscriber is able to communicate as he or she moves within a given region or area. Cellular and Personal Communications Service (PCS) are examples of mobile services. When both parties use a mobile service, the call is referred to as mobile to mobile. Exhibit 3-4 illustrates these types of call scenarios.
In each of the scenarios presented in Exhibit 3-4, the call is switched by a specific entity before terminating to or after being originated by the intercept subject. Law enforcement agencies require access to call content regardless of the entities used to switch the calls. For example, in a mobile-to-mobile or wireline-to-mobile call, the call may be switched at a cell site, at a Mobile Telephone Switching Office (MTSO), or at a Personal Communications Świtching Center (PCSC).
Custom Calling Features. Access to call content includes calls that have been redirected or have multiple call recipients. The obligation of service providers to provide access when custom calling features are invoked depends on whether the service provider that received the authorized intercept request maintains access to the call. When custom calling features are invoked, the service provider that received the authorized intercept request is required only to provide access to call content as long as the service provider maintains access to the communications. When an intercept subject uses a redirection feature that causes the loss of call access by the service provider, law enforcement requires notification of the identity of the new service provider now supporting the subject's communications. If the new service provider's identity is unavailable, law enforcement requires any information that will permit law enforcement agencies to determine the new service provider's identity. In all cases, law enforcement agencies will coordinate delivery of communications in advance.
MOBILITY The requirement for lawful access to call content and call setup information applies equally to mobile telecommunications services. With mobile telecommunications services, a subscriber may move freely within predefined areas and communicate using portable units, terminals, or personal numbers. Law enforcement requires access to an intercept subject's communications throughout the service areas operated by the service provider that has been served with a lawful authorization to intercept. When an intercept subject travels into another service provider's area, law enforcement requires access to ongoing calls only if the service provider maintains access to the subject's communications. When access to the subject's call is not maintained, law enforcement requires the identity of the visited service provider or information that will permit agencies to determine the visited service provider's identity.
The following clarifications and examples focus on cellular communications, which is an existing and well understood technology. However, the requirements apply equally to other mobile communications services.
Handoffs. Law enforcement agencies require continuous access to all ongoing calls regardless of any handoffs that may occur, as long as the service provider retains access to the call
. This includes cases where the intercept subject moves within a service provider's system or between service provider systems. Exhibit 3-5 illustrates the case when an intercept subject, using a cellular service, travels into another service provider's area during an active call. In this illustration, the Mobile Telephone Switching Office serving the end user maintains access to the call and continues to provide law enforcement with access to the intercept subject's communications.
Roaming. The access requirement applies when the intercept subject uses roaming features. This requirement assumes that service providers supporting the subject's communications have received the appropriate lawful authorization from law enforcement and that delivery of the communications has been coordinated. Law enforcement is not asking for an automatic, seamless, nationwide intercept capability for subjects traveling across multiple service provider boundaries. A service provider's network may encompass local, regional, or interstate areas depending on the scope coverage offered by the service provider. However, when a service provider offers a nationwide service and lawful authorizations permit interception, law enforcement agencies require access to communications for an intercept subject roaming within that service provider's network.
Registration Information. Law enforcement agencies require access to information regarding the identity of service providers requesting visit registration authorization for an intercept subject. For cellular services, Exhibit 3–6 depicts the case when an intercept subject travels into a new service provider's area and requests service.