Call cuts off when answered

[TellyMcTellyphone]

We have an 084 number which we forward calls from a digital receptionist to. The 084 number performs a call to multiple mobile phones until one is answered and then connects the call.

If we dial the 084 number from a mobile phone directly then everything is fine. If we use the 3cx system then when the call is answered the call is immediately terminated. 3cx shows the call was answered for 00:00 seconds.

Extra information:

1. We're using an ISDN terminal adaptor.
2. We have tried the 084 number from multiple land lines and mobile phones without issue
3. The 3cx system has no issue with any other number
4. If if dial the 084 number from 3cx directly it works
5. The number only fails if I call the digital receptionist, which forwards to an extension set to forward the call to the external number

Any suggestions on how to gather more information? The number provider is saying the issue must be with the PBX (which I can understand), but I don't know how to diagnose further.

Thanks.

 

[Alphabetic]

You should perform some wireshark captures to see what device is doing what and then work backwards.

You may need to enable verbose mode in 3CX and check those logs to and then any logging on your ISDN adapter.