Nortel 1000 Fundamentals page 63

because the NTAK02BB SDI/DCH card does not support QSIG protocols
for ISL. The DCH interface uses these protocols and their variants, as they
have the following advantages:
•
•
•
QSIG GF Name Display is the only supported QSIG supplementary service.
The ITG feature complies with H.323 Basic Call Q.931 signaling. This part
of the H.323 standard (H.225) defines the messaging used to setup and
release basic calls. A mechanism is implemented to enable the passing
of ISDN messaging through the IP network between the two endpoints.
The call is set up using the H.323 standard signaling with encapsulated
ISDN-specific information. This mechanism allows interworkings with other
gateways.
The DCHIP card provides the tandem between the ISDN signaling and the
H.323 protocol. If the DCHIP functionality is combined with the Follower
card, messages are sent between the DCH Processor and the H.323
Processor. Most configurations split this functionality between the DCHIP
and Follower cards.
(page 63)
Figure 18
Signal flow from the DCH to the H.323 stack
Copyright © 2007, Nortel Networks
.
ISL configuration support
symmetry (incoming and outgoing call messaging is the same)
near H.323 standard
Figure 18 "Signal flow from the DCH to the H.323 stack"
shows the signal flow from the DCH to the H.323 stack.
Nortel Communication Server 1000
IP Trunk Fundamentals
NN43001-563 02.01 Standard
Release 5.5 21 December 2007
ISDN Signaling Link 63