I have a customer who has this topology:

PBX1--->PBX2--->Digital PIMG-->Unity

Both PBXes are Nortel Meridian 1s and PBX2, which connects to the PIMG, is working fine with Unity. We recently added some phones on PBX1 via some tie lines and Unity will intermittently not recognize tones. Has anyone else out there experienced this? I have the documentation from the Unity troubleshooting guide regarding the possible DTMF issues, and we will proceed with those steps on Monday.

On an active call (digital phone to digital phone) on the Nortel Meridian, if one phone presses a key, does the other party hear the tones (this is what the documentation says should happen for feature set phones like the M2616 sets on the Meridian). But my knowledge of Nortel is limited.

The other thing that confuses me is that the documentation for the PIMG integration states for adjusting recording gain (TDM to IP gain in the PIMG):

"Caution: Increasing the recording gain too much can cause the PIMG unit to fail to recognize DTMF tones, which will result in integration problems. If DTMF recognition problems occur after increasing the recording gain, decrease the value in the TDM to IP Gain Adjustment field."

If the gain is TDM to IP and the PBX is playing the tones on the 2616 port, it is the PIMG that is amplifying the DTMF tone and not the PBX. So isn't it Unity that fails to recognize the amplifed DTMF tone and not the PIMG?

Unity 5.0(1)

PIMG Firmware 5.1SU2

Thanks in advance for any insight!