loud buzzing sound on intercom calls

[braymond]

The buzz does not seem to be coming from the RTP stream but more from the phone itself. I ran into this buzz on a T28P that had a headset connected to it. I initially thought it was the EHS (since it uses a Jabra wireless headset) so I connected a corded one and if you answered the phone quickly, the buzz could be heard.

I then unplugged the headset cable and no more buzz. If we answer after the second ring, no buzz.

But then I got report from my customer (last Friday) that they start hearing buzz upon answering. Those phones are T26P and no headset. They've been running for almost a month now. I have restarted the phones except one and will check with the customer if the buzz is gone on those I restarted.

I am using the V71 firmware and I use Freeswitch as my PBX. But it is unlikely an issue coming from the RTP; this buzz is more like an induction within the phone.

I'll go onsite in a few days if the problem still exists so I can collect pcap, syslog and config.bin. I will even record the sound so that people can hear what it does ... pretty annoying sound.