OCS integration into Nortel's CS1000 has prerequisites. Nortel's CS1000 5.0 release and upwards is supported when connecting to OCS.
Some pointers: For OCS to conenct to any PBX, you need the mediation gateway.
From the Nortel side, as they did on LCS, you will have to install the nortel converged office application on an application proxy, so in this case the OCS application proxy. The OCS application proxy relays the messages to the Nortel PBX. This means that you can connect directly without any gateway in between.
Actually the converged office is Nortel's specific gateway to conenct to the CS1000.
If you have CS1000 5.0, you can use the PBX with SIP Trunking directly. You will need to have the SIP Trunks added setup. However for 4.5 and below you will need a gateway (we will be using an Audiocodes gateway for our Pilot).
signaling:
OCS <==> OCS mediation (role) server <==> OCS role proxy MCM <==> PBX (NRS/SRS)
Speechpath
OCS <==> OCS mediation (role) server <==> PBX (CS1000 5.0 )