Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

An echo is heard on IP phones when calls are placed between IP phones and the PSTN through the AS5300 IOS gateway

Core Issue

A test bed was established which consisted of the AS5300 gateway with C542 and C549 Digital Signal Processors (DSPs), DSPware11.32, and Cisco IOS 12.3.17(b).

Calls were made from the Session Initiation Protocol (SIP) network to the Public Switched Telephone Network (PSTN) through the AS5300 gateways, and echo canceling information was collected from sniffer traces on the E1 port on the gateway. Tests showed G165 echo cancellation performed better when compared to G168.

This issue is addressed by these Cisco bug IDs:

  • CSCse29385: G168 echo cancellation degrades echo cancellation, changing ERL no impact

  • CSCse64481: ACOM value not reported correctly


This issue is fixed in DSP version 04.4(21), as well as Cisco IOS 12.4(08b) and 12.4(10a).

In order to obtain the appropriate version of Cisco IOS and the DSP upgrade, open a service request with the Cisco Technical Assistance Center (TAC) through the Service Request Tool.

Version history
Revision #:
1 of 1
Last update:
‎06-22-2009 06:15 PM
Updated by: