On hold music breaking up on one sip trunk but not another

[Jeremy Bero]

Cox Communications SIP trunk started garbling our custom music playlist. Audio drops every couple of seconds. Even if I set MOH back to the default 3CX music, the quality improves a bit but still isn't perfect.

Normal calls have no problems. We have recently upgraded to 3CX v16 but the problem existed before that. We have also already rebooted all phone / network equipment (Cox uses an Edgewater device for converting HFC).

Cox is blaming our audio files.

SIPTRUNK.com is our secondary SIP trunk and the same MOH playlist sounds great on calls through that trunk.

Both are using G.711 U-law codec. I believe this is the only one Cox supports.

Has anyone seen (or heard) this before?

 

[leejor]

I was going to suggest looking at the Codecs, but if you have confirmed that calls on both trunks, in both directions , are using the same Codec (G711u), that that probably won't be the issue. Does this happen both direstions? What about on internal calls, put on hold? Does the music sound OK then?

 

[AWS2P]

@leejor as i understand in previous answer, jeremy said same MOH file works fine with another sip trunk provider on same PBX.

 

[leejor]

Yes...but the two trunk groups may not be using the same Codec on calls in both directions, depending on settings

 

[AWS2P]

Both are using G.711 U-law codec. I believe this is the only one Cox supports.

i was thinking this was the only codec used everywhere

 

[Jeremy Bero]

Internal calls on hold / park sound fine.
Inbound and outbound have the same effect.

I'm convinced it is something on Cox's end but not sure how to prove - possibly capturing using wireshark between the PBX and Cox Edgewater gateway.

Thanks!

 

[leejor]

It's very odd that the audio problems don't happen during normal conversations. I suppose you could Wireshark the trunk and see if there are calls that sound fine, then compare to calls the have an issue.
You could try a completely new audio file, following the recommendations .

https://www.3cx.com/docs/converting-wav-file/
https://www.internetvoipphone.co.uk/blog/convert-wav-file-for-3cx-phone-system/

Have a Cox rep call in over the other trunk, then call in over their trunk, so they can hear the difference (do this after doing a comparison of both trunks yourself, using Wireshark, in the event you've missed something)