SIGTRAN ISDN User Adaptation (IUA) Layer from Flextronics Software Systems provides
functionality to transport ISDN signals from Switched
Circuit Network (SCN) to IP network by back-hauling
the Q.921 user messages over SCTP
(Stream Control Transport Protocol) as per the IETF
RFC 3057. IUA supports both ISDN Primary Rate access
(PRA) as well as Basic Rate Access (BRA) including the
support for both point-to-point and point-to-multi-point
modes of communication. This support includes Facility
Associated Signaling (FAS), Non-Facility Associated
Signaling (NFAS) and NFAS with backup D channel. IUA
enables carriers to exchange the signaling information
ISDN networks systems to VoIP networks, providing smooth
transition of new converged IP telephony services.
ISDN signals are terminated at the Signalling
Gateway (SG) from where the IUA transports Signalling
Information from Q.921 to the Q.921 user (typically
Q.931, Q.Sig) at the Media Gateway Controller (MGC).
IUA provides same set of services as Q.921 to the user
at the MGC. Th back hauling of signals is completely
transparent to the Q.921 user and it runs as it would
be running directly over Q.921.
