Simple Message Desk Interface message. It contains specific call information:
•       the origin (caller)
•       destination (who the call is for)
•       the reason the call was received:
•       CF (call forward)
•       CFNA (call forward no answer)
•       CFB (call forward busy)
•       the port on the Brooktrout card where the call is waiting to be processed.
The SMDI information is passed to Voice Services  so the call can be accurately processed. The SMDI message can be created by the Connected Systems PBXLink, or for systems that do not use a PBX link (Centrex systems), it can come directly from the switch via an SMDI line.