Instruction manual

Direct Inward Dialing (DID)
Issue 4 May 2003 129555-233-767
Communication Manager supports two versions of digital multiplexed interface,
each differing in the way information is carried over the 24th channel:
■ Bit-oriented signaling
■ Message-oriented signaling
Bit-oriented signalling
Digital multiplexed interface bit-oriented signalling carries framing and alarm
data and signalling information for connections to host computers and other
vendor equipment.
Message-oriented signalling
Digital multiplexed interface message-oriented signalling, fully compatible with
ISDN-PRI, uses the same message-oriented signalling format — link access
procedure on the D-channel — as ISDN-PRI for control and signalling. These
signalling capabilities extend the advantages of digital multiplexed interface
message-oriented signalling multiplexed communications to the public ISDN
network.
Direct Inward Dialing (DID)
Direct Inward Dialing (DID) trunks connect Communication Manager to the local
central office for incoming calls dialed directly to stations without attendant
assistance.
Direct Inward/Outward Dialing (DIOD)
Traditionally, Central Office (CO) trunks and Direct Inward Dialing (DID) trunks
interface a PBX with a central office. A CO trunk services outgoing calls and
accepts incoming calls that are terminated at the attendant. A DID trunk is used
for calls that need to be terminated without an attendant interaction.
E&M signaling — continuous and
pulsed
See ‘‘E&M signaling — continuous and pulsed’’ on page 100.