Note the following restrictions when integrating an Octel system with Cisco CME:
One FXS port must be dedicated for MWI operation.
The Octel system must have analog ports and must be configured for analog DTMF integration. Digital and Simplified Message Desk Interface (SMDI) integration with CME is not supported.
The Octel system does not distinguish between extension-to-extension and trunk-to-extension transfers. Thus, you must configure the DTMF patterns for these transfers with the same values on the Cisco CME system.
The MWI ephone-dn must use the . wildcard rather than the T wildcard to specify the exact extension length. Also, you must use an asterisk before and after configuring the called party ID (for example, number 3000*....*).
and if u have the voiceMail connected to a PBX and ur CME connected to the PBX
u were right u need to forward the call to the PBX and the PBX will forward it to the VoiceMail in the CME u just need a pots dial-peer with distination pattren as the voiceMail number and point to the port connected to the PBX
good luck
please, if helpful Rate