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Weirdest problem ever: Forwarded calls get cancels after 27 seconds total

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noord

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Hello all,

Well, I have the weirdest problem. 3CX support and my trunk provider also can't seem to figure it out, so I'm posting it here in the hopes that someone has a suggestion.

Situation is as follows:
-1 Extension
-1 Trunk with one phone number directly connected to Extension 10
-Extension 10 is set to forward to 'my mobile' after 20 seconds

If the phone number of 3CX is called, it goes as follows:
-Extension 10 rings for 20 seconds
-Mobile phone rings for 7 seconds
-Extension 10 rings for 20 seconds again
-Mobile phone rings for 7 seconds again.
This repeats itself.

You can answer the Mobile phone if you want and have a normal conversation.

Now, the strange thing is, when I set the 'forward after... ' time to 10 seconds, it goes as follows;
-Extension 10 rings for 10 seconds
-Mobile phone rings for 17 seconds
-Extension 10 rings for 10 seconds
-Mobile phone rings for 17 seconds.
This repeats.

In both examples, you see the time adds up to 27 seconds.
And I can reproduce this and vary this. Set 'forward after...' to 5 seconds and the mobile rings for 22 seconds. Set it to 25 seconds and the mobile rings for just 2 seconds....

I have Wireshark captures sent to 3CX and those captures show the CANCEL coming from the trunk provider. I can believe that, I see it to. HOWEVER, why does the trunk provider cancel the call? And how can they possibly know after how many seconds they "have to" cancel the call to make a grand total of 27 seconds? This just seems impossible. The trunk provider is saying the problem lies with 3CX, 3CX says it lies with the trunk provider....
Normal calls through the trunk provider obviously go well and never get canceled.

Does anyone have any idea how on earth the trunk provider 'knows' exactly when to cancel the call? In some manner 3CX must be specifiying this, since only 3CX knows what the 'forward after' time is set to?

(one more remark, I have also tried setting up a Ring Group that forwards to an external number. The result is almost the same, difference being that after the 27 seconds have elapsed, the call is completely terminated. Eg. the 'return' to ringing all extensions in the Ring Group does not occur, but the external forward is canceled in exactly the same manner).

Attached are two screenshots showing the point a bit more clearly, I hope!
 

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Do you experience the same time out period if ...you use the Ring My Mobile at the same time option, or, if you forward to a landline (not your mobile) number?

Why the 401 Unauthorized message coming from your provider?
 
We had a similar problem... believe it or not a full server and system restart fixed it!
 
Are you able to dial your cell phone from that extension and have a call last more than 27 seconds ?
 
Thanks for all questions and suggestions.

I'll answer them one by one:
Do you experience the same time out period if ...you use the Ring My Mobile at the same time option, or, if you forward to a landline (not your mobile) number?

I do not know, I have not tested it in this manner (ring my mobile at the same time).
If I forward to a landline or mobile phone at another provider, the same thing happens. It doesn't matter which number I forward to.
Only difference is that when I use a Ring Group to forward the call, the entire call is terminated after 27 seconds. The person making the call in the first place then gets a message from their provider stating 'the number you have dialed, cannot be reached. Please try again later' or just the 'beep-beep-beep', depending on the provider making the test-call.

Why the 401 Unauthorized message coming from your provider?
That is normal behaviour, the first time the call is requested, the provider sends a challenge, 3CX calculates the response and then requests the call again using the response as authentication. This is by design.

We had a similar problem... believe it or not a full server and system restart fixed it!
I have reset the services many times of course, but not yet the entire server.
I have just reset the entire server and tried again, but the problem persists.

Are you able to dial your cell phone from that extension and have a call last more than 27 seconds ?
Yes, no problem. I can dial any number 'the normal way' and they all ring 'indefinately'.
Also, when I answer the mobile phone when it's forwarded there, I can have a conversation for as long as I want.
---

If anyone is interested, I can of course end you the WireShark trace, logfiles and some screenshots indicating the issue via PM.

Thanks a lot!
 
are the phones and pbx behind the same router and on the same subnet ?
... I've actually seen faulty switches (or bad firmware on a switch) cause things like this.
Did you un-check the "disconnect inbound calls after 27 seconds" box in 3cx advanced paramaters? (just kidding on that one, obviously)

Looking forward to getting this solved / finding out what the problem is. Screams "network issue" to me ...
 
I don't suppose you have a second provider, to test route the call(s) out on?
 
Hi noord,

As I can see on all cases the Provider sends the CANCEL message to the PBX. Based on this and since this is a termination message, there is nothing you can do or change something on your 3CX PBX side. In order to determine the cause of this issue and fix it, is to contact with your Provider. As far as I can see on our Ticket system, you opened a case and what I can see my team leader explained you this issue comes from your Provider. This is your TicketNumber: 132263.
To save your time, here there is nothing we can do to help you. Please investigate your issue with your Voip Provider.
 
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