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Handbook for California and Nevada

Calling Party Identification for Facilities-Based CLECs

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Calling Party Identification for Facilities-Based CLECs

Important: The material contained in this section is for Facilities-based CLECs only. CLEC-Resellers who purchase Resale services must refer to the Ancillary Services section of the Handbook for information about Handling Annoyance Calls, Emergency Traps & Back Traces on Resale Access Lines. 


Using a Trap

Directing Law Enforcement

Coordination Between CLECs

Successful Traps

AT&T Nevada


Within AT&T West’s Network there are three categories related to calling party identification:

  • Annoyance Calls. AT&T California's Annoyance Call Bureau (ACB) investigates potential violations of California Penal Code section 653m for its own EUs. Because the investigations rely on placing traps at the switch, AT&T California cannot perform this service for Facilities-based CLECs' EUs. 

However, in the course of finding the source of an annoying call for an AT&T California EU, the ACB may require the assistance of a facilities-based EC, or of an IEC or LEC. Likewise, a Facilities-based CLEC may require the assistance of AT&T California's ACB, or of an IEC or LEC. 

  • Court-Ordered and Emergency Situations. To the extent that AT&T California can comply with court orders and respond to emergency situations, it does. When the telephone number comes from a CLEC with its own switch, AT&T California directs the law enforcement agency (LEA) to go to the appropriate CLEC if it is unable to comply with the order. 


  • Tariffed services, such as Caller ID or Call Trace. These services are provided directly by the Facilities-based CLEC, and are not discussed in relation to Facilities-based CLECs in any section of the CLEC Handbook. [Refer to Section Resale optional Feature: Custom Calling Service - Call Trace for information.]

Using a Trap to Identify a Caller

A trap is a call capturing technology at the switch which gathers calling party information. A 'terminating trap' is located at the switch for the telephone number of the EU receiving the calls. It can identify the Calling Party Number (CPN) if the CPN is from that same switch.

If the CPN comes from another switch, the terminating trap may or may not capture the CPN. If it does not capture the CPN, the EU's CLEC requires the assistance of other carriers, such as: 

  • Another local exchange carrier (such as AT&T California, through its ACB) 
  • An CLEC-Reseller (who has a Resold service, through a LEC such as AT&T California) 
  • Another Facilities-based CLEC  
  • An Interexchange Carrier (IEC)

Based on information provided by the EU's CLEC, the other carrier places an 'originating trap' to capture the CPN.

Note: There may be times when the ACB requires the assistance of the Facilities-based CLEC. 

The EU's CLEC has to 'filter' subsequent calls from its trap to see if a match can be made with the CPN responsible for the annoying calls. 

Directing Law Enforcement Agency (LEA) to Appropriate Carrier
If a carrier (including AT&T California) receives a request to identify the CPN for an EU who is not a customer of that carrier, the carrier should direct the LEA to the appropriate carrier, if known.

Coordination (Assists) Between LECs/IECs/CLECs

Filter information often originates from Local Exchange Companies (LECs), Interexchange Carriers (IECs), and CLECs. In such instances, LECs/IECs/CLECs are requested to assist in establishing an originating trap.

Note:  An originating trap is required if the call goes through one or more Central Offices, or Tandem switches. 

Subsequent dates and times are forwarded to the LEC/IEC/CLEC for identifying call origin. Mutual trap and filter assistance is required (as CLEC subscriber victims may be called by AT&T California subscriber suspects and vice versa) until Calling Party Number (CPN) may be passed between companies. This type of coordination is referred to as an 'assist.' 

When an assist is requested, the CLEC must: 

  • Identify the switch from which the call is coming. For ported numbers this would be the actual switch, not the one associated with the NPA-NXX.  This is done by giving the Common Language Location Identification (CLLI) code, or a similar identifier. The CLLI code is a unique 11-digit alpha/numeric name given to each switch. 

Example: LSANCA01DS0 = Los Angeles, California, central office #01, digital switch #0. 

  • Provide the police case number, as required for California Penal Code 653m violations. (Refer to Section 193.3.1 Definitions of California Penal Code 653m Violations for information.) The following information is also required, in addition to the police case number: 
  • Police jurisdiction in which the 653m violation took place. 
  • Name and telephone number of the police officer who took the report.
Information Acquired from Successful Traps

When the Facilities-based CLEC has requested assistance from the ACB, and the ACB has a successful trap, the suspect information is released to the Law Enforcement Agency (LEA) where the 653m case was filed. This information is the:

  • EU's Telephone Number 
  • Billing Name 
  • Service Address

This information is given only to the LEA; it is not given to the CLEC or the CLEC's EU.

AT&T Nevada

AT&T Nevada follows the same general guidelines for managing annoyance calls, court-ordered and emergency situations and traps