IP-PT call quality degrading

[kieran_f]

Hi there,

we have an NS1000 with a stacked TDE600. We seperated the Lan that the NS1000 was on to give a dedicated link to the SIP trunks. Anyway, we have an issue where all the IP-PT extension calls have the quality degrade after a seemingly random period of time.

Digital extensions are totally fine and SIP doesn't loose registration.

If we reset the V-IPEXT card, everything works as normal then a few minutes (anything between 2 and around 40 minutes) calls begin to break up until you cannot hear anything.

We swapped out all the network equipment, stripped everything down to just the phone system and extensions, and it still happens. I have no idea why this is happening, and while I suspect a bad DSP, it has had no impact on the quality of SIP trunk calls from the digital extensions.

Really scratching my head at this one. Any ideas??

 

[obtsystems]

Are the ip phones on a different subnet than the sip trunk. If so are you using the wan port on the ns for the sip

Unlikely to be dsp if sip is on on the digital phones

Do you have a pcap trace

 

[kieran_f]

Hi - I don't have a pcap. The IP Phones are connecting via media relay. Only certain sites were affected. We put these back on a VPN connection and now they are working fine but it's confusing as to why they weren't working on MRG.

 

[obtsystems]

Do you have a vpn to the office with the system and the phones your using the media relay at the same time as we have found it causes problems because you are trying to go through the wan when there’s a route to the system internally. The phones will try to go peer to peer and the system is trying to use the media relay

 

[phones001]

I have a site that also has this problem with every few weeks the off site IP phones lose audio or have very bad audio until the router at the main NS700 is reset then they work fine. They do have a data VPN running to one of the sites. What is the recommended setup when you have multiple sites, some with hardware VPN and others without all connecting to a single NS700 with off site phones.

 

[obtsystems]

What makes is the router, have to be sure all sip helpers and ALG are turned off

If there’s a vpn, I would use it and media relay if not. If you have 2 sites with vpn back to head office you should have a vpn between them too for the Ip phone to go peer to peer