This document describes the issue when calls that come in to Slave T1 IP Media Gateway (TIMG) or PBX IP Media Gateway (PIMG) are not routed correctly. TIMGs and PIMGs make it possible for PBXs to integrate to Unity Connection for voicemail access. Some PBXs require that this integration be via Simplified Message Desk Interface (SMDI), MCI, or MD-110. This means that calling information will be passed via a serial port connection from the PBX to the TIMG or PIMG. The TIMG or PIMG that the serial cable connects to will be configured as a Master. If there are other TIMGs or PIMGs required, these will be configured as Slaves and will look to the Master for calling information.
There are two or more TIMGs/PIMGs with a Master and Slave configuration. When a call comes into the Master, the call is forwarded to the proper Unity Connection voicemail box greeting.
Here is an example screenshot of the page from a Master PIMG:
However, when the call comes into the Slave TIMG the call is answered by the Opening Greeting. The call rolls to the Opening Greeting because the invite sent to Unity Connection from TIMG does not have a 'Diversion:' line within to say which mailbox extension the call should go to.
Here is an example of calling information seen on the Master:
This happens because the calling information is forwarded across the serial cable to the Master TIMG/PIMG, but the Logical Terminal Number (LTN) information does not match up to the port on the T1 Central Authentication Service (CAS) the physical call came in on.
On TIMG, select Configuration > Serial > Switch Protocol in order to configure the Logical Extension Numbers for each port.
Match the TIMG LTN and the port number from the PBX setting. The PBX has a table that shows you which channel on which T1 CAS line uses which LTN. Determine this information from the PBX first and set it accordingly in the TIMG. It is possible to use LTN 1-24 for Master channel 1-24 and LTN 25-48 for Slave channel 1-24.