Echo between IP phones within same IP network

[esther.tan]

Hi

I have a client who is on CM6. They just feedbacked to me that one of the user complained about hearing echo when she called another internal user (IP phone to IP phone). At the moment, only one user is experencing this problem.

The users are all on the same network, same LAN, same vlan (working in the same office building). We have asked her to try lowering the volume of her phone, but it doesn't seems to help. User is not using speaker mode when she called the internal party.

Would really appreciate any advice.

Thanks

[a-vazquez]

The solution is to configure and verify echo cancellation operation on a Cisco IOS gateway. The echo canceller in the voice gateway cancels the echo heard by the IP phone user.

Echo is adequately controlled, which implies that echo cancellers are used. Echo cancellers are required when one-way delay exceeds 25 ms

http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080149a1f.shtml#ipphoneecho