Echo/Side tone on SV8100 Calls 1

[nds50]

Have an SV8100 installed about 6 months ago and it has developed an echo when the user is on the CO lines. The user said that their voice is back feeding to them and there is a lot of static at times. When to site and reproduced the problem. Checked the CO lines with a Sidekick meter and line current and noise levels were well within limits for POTS service. The stations are IP phones.
The problem with the problem is it doesn't happen on every call and the echo/back feed declines the longer the conversation.

 

[MercuryComm]

This is a known issue having analog CO lines and IP phones. I think upgrading the software to Ver. 4 will correct this issue.