NEC SV9100 Outgoing Calls Strange Audio Latency

[Maganac]

Hello, apologies in advance, I am rather new to VOIP systems and so my I may come off as confusing to those who know better.

First off, we have been having a strange issue this past week with our phones. Incoming calls are having no problems at all as far as I am aware, however whenever some users are making outgoing calls, the receiver on the other end receives an audio latency that sounds like we are slurring our words. On the other hand, we can hear them just fine.

I have tried some basic things here and there to see if it clears ups:

[ul]
[li]Unplugging effected phones[/li]
[li]Power cycle the NEC[/li]
[li]Had the modem for the system switched out[/li]
[/ul]

I also did a power cycle for the firewall that is attached between the NEC and the modem, but currently don't know if it fixed the problem. Calling cell phones here does not seem to be a clear indicator of performance, as they sound clear before and after regular outgoing calls have problems and calling VOIP testing numbers and doing echo tests haven't given me a clear indicator if the system is fine or not as well.

 

[CoralTech]

SIP trunks?

 

[Maganac]

I will try to troubleshoot that.

To add further context, this system was setup back in 2017, so I have no context on how the whole thing was configured and the original person who was part of it left some time ago. The VOIP service was even changed sometime between the original guy leaving some years ago and me just entering here last year, so I am working with a lot of missing information.

 

[CoralTech]

Well, if the latency is ONLY on external calls look there.

 

[Daniel_RO]

Have a look in 84-13-28 and also 01, 07, 33, 38 - This is codec and frame sizing you are sending out
I would also confirm your Diffserve is setup in 84-10 for RTP/RTCP and SIP Trunk

On outgoing calls, it is your system initiating the calls, and as such, sets the precedence for timers and QOS, if the above settings dont match what your carrier expects, or a sort of standard you may see latency on your calls out, but not the calls in.