Calls dropping at random

[randybell]

3cx v15 Windows

I am experiencing calls just dropping mid sentence on several phones in the same office, the logs show user hangup. But users are not hanging up. All calls are going through a PSTN 4 line gateway to analog lines, so they are not going through the firewall at all. Phones are yealink t32/t38g/t42g/t41p

View attachment 5646

I have been in discussed for days with 3cx support, but they are so far unable to see anything wrong.

An office of 21 phones and are getting 10-20 dropped calls out of about 80 per day.

Any suggestions

 

[lneblett]

What make and model of gateway and what firmware version?

From a 3CX perspective, the call from a gateway at the SIP level is really no different than a call to/from one of the Yealinks, Presumably all are on the same LAN and I also assume no drops are experienced when calls are placed from/to another extension. This tends to point to the gateway/3CX path.

The portion of the capture you posted is only showing that portion of the call between 3CX and extension 302, it is not showing that between the gateway and 3CX. What the log is showing is not that your extension user hung-up, but rather that 3CX told the extension that the call had been completed - Cause - BYE received from 172.XXX.XXX.XXX. As a result, it appears that something caused 3CX to believe that the call had been terminated. The BYE is simply a way for the system to tell the phone the call has ended, it does not necessarily know the circumstances by which the call ended, but to the phone it is not important, it only needs to know that it has and nothing else will occur related to that call. It is a final response.

It would be ideal if you could get a wireshark capture of a dropped call - understand that it is random and may be problematic, but at least we will be able to see why 3CX thought the call ended. It could be that the gateway is going bad, the PSTN line(s) may have an issue, the gateway is no longer optimized to the PSTN line conditions, etc.

 

[leejor]

Are these only outside calls? If so, check the disconnect options on the gateway, especially if you have it set to drop the call on a certain length of silence.

 

[randybell]

yes only on outside calls. It's a welltech 2540, I see the 2 disconnect options, but the settings seem to be what welltech documentation says they should be for. Anyone have ideas where these other disconnect options might be?

I replaced the pbx and the welltech gateway last night just in case. But I have reports of the same problem today.

 

[leejor]

As suggested by Ineblett, you may wish to use Wireshark to narrow down what is causing the calls to drop.
You say you've replaced the gateway and PBX, what else, on the network (router, switches), can you easily replace or bypass, to eliminate them as a cause?