Calls not always initiating / failing

[TimElse]

Hi everyone,

I'm new here and was wondering if anyone could shed some light on an issue that we have been having here since deploying 3CX to our business. We are a small to medium size business approx 40-50 users and we deployed 3CX a few weeks ago and for the most part it has been excellent, however, we have had an ongoing issue where when staff will be attempting to dial out externally it seems to hang for 10-20 seconds before eventually timing out and returning the attached error message in the 3CX client, stating "Call Failed, Server Internal Error".

If the user attempts to call again sometimes it will dial through successfully but sometimes they need to dial the same number several times to ring out, the call can also cut out for users when they are party way through leaving a voicemail too.
Looking in the event logs at the time which this coincides and I see the following: Call or Registration to 07531742932@(Ln.10000@VoIPProviderDomain) has failed. [ V4 0.0.0.0:0 UNKNOWN_TRANSPORT target domain=unspecified mFlowKey=0 ] replied: 503 Service Unavailable; warning: ; internal

I have omitted the voice provider domain purposefully, this occurs frequently throughout the day, call quality is fine during a call so I'm not thinking it is a QoS issue. All relevant TCP and UDP ports are open on the firewall. I have wireshark captures of the time this is happening, if there is any more information I can provide that could help somebody to shed any light on this problem please let me know. Any help would be much appreciated.

Many thanks,
Tim

 

[leejor]

Since this has been happening from day one, it could be a number of things, including network hardware. You may have to do some substitution to determine if it is hardware. I would go the easy route first. Talk to your provider and see if they are seeing anything out of the ordinary. If you have another provider to use, for testing, then you could try that. There are some free VoIP services that allow completion to toll free numbers in various countries. http://www.sipbroker.com/sipbroker/action/login They can be useful just for testing.

I assume that internal calls are functioning correctly?

 

[TimElse]

Hi Lee,

Thanks for your reply, our VoIP provider have been looking into this so I'm assuming they'd have mentioned something, but I will ask the question anyway just in case. The sipbroker route sounds interesting, can this be isolated from the other sip trunk, we would need all other calls to continue as normal unless we did this out of hours.

I've attached a screenshot from the event viewer on the PBX server which is running on a Windows Server 2008 VM host.

The errors are typically 480 (Temporarily Unavailable), 408 (Request Timeout) or 503 (Service Unavailable) and occasionally 404 (Not Found- NoRoute Found). Occasionally reception have also complained of inbound calls failing.. i.e. they'll ring briefly for a second or two and then the call will just stop.

Could this be a routing issue on our side?

 

[leejor]

You may want to employ a tool such as Wireshark, during a quiet period, to see what is happening on the WAN side of the PBX during a failed call.

As far as testing with SIPBroker. If you have a toll free number that you can test with, you can always create specific outbound rules that will only send that number, or multiple numbers over the new route. If you do some searching there are a number of VoIP providers that are more than happy to take all your traffic to toll free numbers, as they get a "piece of the action". It cost you nothing but gives you an additional route for comparing calls to your normal provider, or a backup/overflow route.

 

[AndreasP_3CX]

Hi Tim

A wireshark will indeed show you whether this is due to the Provider not being registered whether all your routes are busy, whether your provided is not responding back etc. This however would need a continuous wireshark capture since the issue is not replcable at will. Is your provider IP based? Registration based? Is he even seeing the outbound calls?

Best Regards