ABSTRACT: GR-1270 replaces TR-NWT-001270, Issue 1, May 1992, and Revision 1, December 1997, but contains NO TECHNICAL CHANGES from that original document. It has been issued strictly to conform with the new Telcordia Technologies document format and GR process, and carries a new issue number and date.

GR-1270 contains the Telcordia view of generic requirements for call-by-call selection of the listed services provided to Class II Equipment served by an ISDN Primary Rate Interface (PRI). It completely replaces TR-NWT-001270 and its revision and bulletins.

Call-by-call service selection is a method of providing services to Class II Equipment on an ISDN PRI. Call-by-call service selection is an alternative to providing services on a dedicated interface, a dedicated B channel, or a dedicated group of B channels basis. Any B channel on the PRI can be used to offer provisioned services on a per-call basis.

Requirements of call-by-call selection need to be defined for each service. This document only describes the generic requirements of call-by-call service selection for a limited number of services. Future documents will provide the generic requirements for offering additional services on a call-by-call basis.

This document contains generic requirements for the following call-by-call services.

• Foreign Exchange Selection
• Tie Trunk Selection
• OUTWATS Selection
• INWATS Selection