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DTMF echo causing voicemail system to go to incorrect box


3660 terminating PRIs to a Meridian and to the PSTN. A VG248 is connected to a Siemens voicemail system using 2-wire connections with SMDI to a Call Manager.

Calls from an IP phone to the Voice mail system work ok. Calls from the PSTN and the Meridian fail most of the time; the VM system is apparently hearing the DTMF tones multiple times and interpreting that as the voice mail box being accessed. For example, trying to access VM x43333# will often fail because the Siemens gets 444433 and aborts. Adjusting digit cadence doesn't seem to have an effect on whether the Siemens gets the DTMF correctly.

The input and output gain on the VG248 has been reduced to -6db and -14db, and we've tried to change the echo cancel from SLIC to DSP, but no effect.

No idea if there are any gain setting that can be modified on the Siemens - it's mostly a black box.

All systems are located fairly close together, so this isn't a transcontinental issue.

Any recommendations for troubleshooting this? The next logical place to start adjusting is the 3660, since it's the more likely place to be causing the problems.


Re: DTMF echo causing voicemail system to go to incorrect box

Often times complex troubleshooting issues are best addressed in an interactive session with one of our trained technical assistance engineers. While other forum users may be able to help, it’s often difficult to do so for this type of issue.

To utilize the resources at our Technical Assistance Center, please visit and to open a case with one of our TAC engineers, visit

If anyone else in the forum has some advice, please reply to this thread.

Thank you for posting.

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