AT&T DS1/DMi/ISDN-PRI manual Backup D-Channel, Codeset, User-to-User Information transfer

2-14NETWORK CONNECTIONS AND CONFIGURATIONS

Dial Tone

Second dial tone may be provided by a 4ESS. However, it is recommended that the customer- premises switch provide a second dial tone. With this arrangement, the second dial tone can be provided through use of the ARS feature on all ISDN-PRI trunks that terminate on a 4ESS.

Touch-Tone Capability

ISDN-PRI does not support either dial pulse addressing or touch-tone signaling, but provides the equivalent capabilities with ASCII character signaling on the D-channel.

Screening Intra-LATA Calls

A 4ESS can be used to block intra-LATA calls. However, all System 75, System 85, Generic 1, and Generic 2 special-access applications should use the ARS feature to screen outgoing calls. By using the ARS feature, only inter-LATA calls are routed to a 4ESS.

NFAS

Nonfacility-associated signaling is supported by a 4ESS. From a Generic 2 perspective, there are no restrictions with this capability.

Backup D-Channel

The D-channel backup is supported by the 4ESS. From a Generic 2 perspective, there are no restrictions with this capability.

Codeset

Both 4E11 and 4E12 receive and transmit UUI data in codeset 7.

4ESS receives and transmits UUI data in codeset 6. However, it will still tandem codeset-7 information.

User-to-User Information transfer

To pass user-to-user information (UUI) through the ISDN public network, all 4ESS-to-4ESS links must be implemented with CCS7. If as many as one link is implemented with CCS6, then UUI will not be passed.