SIP Trunk and Digitial Receptionist Problem

[CRAFSL]

Hi,

We had a the same problem a few months ago where you would dial the main number it would go to the digital receptionist but then you couldn't press the button from the menu or dial the extension number.

The problem only appears to happen on Iphones on 4G with VoLTE switched on. But it now happens on both the configured SIP trunks. I have turned the VoLTE switch off and it works ok and I have tested from Android phones and they work straight away.

I initially thought I had fixed it by removing the support re-invites from the SIP trunk configuration but this now doesn't work for either SIP trunk.

You mentioned before it could be an issue with CODECs is this something that can be looked at?

Currently running on V16.0.9

Thanks

Chris

 

[YiannisH_3CX]

Hi @CRAFSL

It looks like a DTMF issue where the button presses are not transmitted correctly to the PBX. Without looking at what is coming to the PBX is hard to troubleshoot so the only thing I can suggest right now is to upgrade to V18 where we made some big improvements in our media server to help with these kinds of issues.
Not sure if this will solve your issue but it might.

 

[leejor]

You would have to examine the SIP messages (Wireshark?) from, the mobile to determine what type of DTMF is being used, whether that is a SIP message, or, is being sent as audio. If it is being sent as audio, and a low bit rate Codec were being used, then that can cause issues.

 

[CRAFSL]

I will update to V18 as it is something on the list to do anyway and try again. I will revert back once done and tested.

Just a strange one as it used to work without any issue.

 

[leejor]

The problem only appears to happen on Iphones on 4G with VoLTE switched on.

It would appear that that combination, is the issue, for some reason. As more carriers switch to VoLTE, I don't doubt that there may be more issues,crop up, in the future.