sundance-communications.com/forum Forums TDM Business Telephone Systems Samsung Telephones & Systems echo on co line using tandem trunking

We have a problem when we try to use LCR to call in another city. At node A we have a iDCS500r2 and node B we have iDCS100r2. If we use a direct intercom call between the 2 node there's no problem but when we try to use a co to place a local call at the other node we get a lot of echo.
Does anybody had already fix that problem?

The link for IP communication is a T1 and we have QOS already enabled.

Thanks

Your problem here is delay. IP (4 wire) to analog (2 wire) conversion can get delay if the CO loops are long. I would check first of all to see if you have the same problem calling from node a on node b's lines and viceversa.. it may only be 1 side that is bad. If that is the case, then I would look at converting the side that is bad, )ie the side with the outbound trunks that echo) over to a channel-bank. This usually means switching service providers. If the problem can be found on calls from either side, then I would test the connection on the t-1 and see how long it takes for traffic to pass. The Central Office will usually do this test for you if you tell them you are having problems. As far as codecs go, you could try switching from the default g.729a to g.711 for your networking, this is found in MMC 841, I believe. The basic cause of echo on IP is delay. Eliminate delay and remove the echo.

You have qos enabled on the phone system but is it enabled on the routers.?

Like bacherjr said you may have one system with the timing off but you will need to do more diagnostic work to see which one.

added is the T1 point to point and voice only? or shared?

It make sense that it could be delay on the T1. But i have no choice about the service provider because node b is in a very small town in the middle of nowhere!! I will check the link with the service provider.

Can i correct echo with settings in mmc 835? If yes, whath is the effect of each settings because Samsung docum is a little bit poor about that.

Thanks a lot for your help!

echo cancel is what you want to play with in 835.

you can try the silence suppresion but I dont know if that will fix it.

jitter options will adjust the buffer between sent packets eg: if there are three switches between node a and b you might want to increase the jitter or reduce it to account for the hops taken. :thumb:

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