Audio bleedthrough problems

Unanswered Question
Jul 25th, 2007

I have customer with two audio bleedthrough problems on a CME 3.2.1 system (I realize that we're a little bit behind, here).

The customer says he's recently noticed that he can occasionally faintly hear a PSTN conversation taking place on another IP phone. The only PSTN connection is a PRI ISDN circuit. Is this even possible? Once past the DSP in the IP phone, where in the call flow is the audio even analog, so that it could possibly bleed from one call to another? Does the DSP actually convert the G.711 to analog audio then back to PCM u-law, or does it just transcode G.711 to PCM u-law?

Second problem, this one has been going on for a while. When someone is talking on a 7960G handset with the volume turned all the way up, the audio bleeds faintly out through the speakerphone speaker. I've seen other people post about this problem on various forums and mailing lists around the web, and I've seen some people allude to a fix in the phone's firmware, but nothing definitive. Has anyone else had this problem? Did a newer phone load fix it? Is this another DSP problem (the one in the phone this time), or is it a fundamental design problem (i.e. unshielded wires in the handset's speaker circuit physically too close to the speakerphone circuit, bleeding over via EMI)?

Thanks in advance to anyone who can answer any of these questions.

I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
rob.huffman Wed, 07/25/2007 - 13:17

Hi George,

This is related to your second issue;

CSCef53862 Bug Details

Faint audio is heard in the speaker while using handset


Faint audio is heard in speaker when handset is used


Hanset volume level is set at max.

1st Found-In












Hope this helps!



This Discussion