ISDN Protocol Administrator's and Developer's Guide ... - Intervoice

Table 6-1. DPNSS 1 Network Layer Messages (continued)Symbol Message Type DescriptionSM Swap Message Requests a change from the current service mode to a new mode asshown by the Service Indicator Code (SIC)This message can also be used to acknowledge another Swap.SCIMSCRMSSRM(C)SSRM(I)Single-Channel ClearIndication MessageSingle-Channel ClearReject MessageSubsequent ServiceRequest Message(Complete)Subsequent ServiceRequest Message(Incomplete)Acknowledges an SCRM.Initiates the clearing sequence of one of the calls on a channel beingused by two calls.The call that will be released is indicated by a SupplementaryInformation String within the Indication field of the message.Upon receiving an SCRM, a PBX releases the indicated call andreturns an SCIM to confirm that the channel is now being used by asolitary call.Sends additional selection information that is not included in apreceding ISRM(I), ERM(I), RM(I) or SSRM(I) message.No further SSRM messages can be sent after this message.Sends additional selection information that is not included in apreceding ISRM(I), ERM(I), RM(I) or SSRM(I).An indefinite number of SSRM(I)s can follow an ISRM(I), ERM(I) orRM(I); the sequence is normally completed by an SSRM(C).The D Channel carries all data across the network. This is similar to theD Channel’s function in ISDN.6-4 ISDN Protocol Administrator’s and Developer’s Guide 60001262, First Edition