Voice quality and Low volume

[sridhark]

We've a central location and 3 branch locations. The central location have a 3640 router connected to an EPABX using E&M port connection. The remote locations have 2610 router with E&M card and 2FXS ports. Communication to one of the remote location is absolutely fine, problem is with 2nd location which has similar hardware and setup as the first location (2610 router, E&M card).

The remote locations are connected to the central location with a 64Kbps leased line, being used only for voice (no data at all).

At this remote location, volume is okay for 2 calls. As soon as the 3rd call is placed to the central location, voice vol goes down.

As a first step we have removed the E&M and replaced with FXS ports and tested. The volume is okay on the 3rd call, the voice quality goes down as soon as 3rd call is placed.

We then suspected the leased line, tested the bandwidth and found to be 64Kbps.

Codec configured on WAN interface is 729r8.

Request your help in resolving the issue.

Thanks in anticipation.

rgds

[fbahram]

First , if you have 64k and you are using "no RTP header compression" then you need to set aside 24k / call , for 3 calls, that would be more than 64k (24x3=72) therefore the third call quality will degrade and most likely cause the other 2 calls to degrade also.

If you are using header compression, then you can try to adjust the volume on the side that you hear the low volume, by configuring the far gateway (opposite side of the low volume phone) with input gain of 3db, then 6db, and each time, shut/no shut the port and try again.

You can also put negative output attentuation (-3db, -6db, etc) on the router closest to the low volume phone.

Hope this helps.