Unable to configure SIP transport type (3CX Standard)

[NTQ_SD]

Hello,

We have experienced an issue where 3CX SIP trunks have been intermittently failing on 3CX installations. After some troubleshooting we've discovered the reason is that when 3CX fails to complete the SIP trunk registration with UDP it will automatically retry using TCP mode for the SIP transport.

The issue here is that our upstream SIP provider actively rejects registrations attempted using TCP. 3CX appears to see this as having provided incorrect credentials, so gets stuck on trying to register using TCP. To resolve this (when it occurs) we have to disable and re-enable the SIP trunk(s) to get it to toggle back, to get it working .

On 3CX Professional we have the option to control the SIP transport mode per trunk (which seems to resolves this), however this option appears to be missing on 3CX Standard installations.

Is there any way to configure the SIP transport mode for trunks configured on 3CX Standard?

 

[JohnS_3CX]

In V16 if you go to your SIP trunk, under the options tab, there is transport protocol which is probably set to "any" at the moment. You can just switch it to UDP from there:

 

[NTQ_SD]

Hi John,

Thanks for taking the time to respond.

Unfortunately this option does appear to be missing / hidden from the 3CX setups we having running 3CX v16 Standard (see image below).

i.e. SIP Trunks -> Select Trunks -> Edit -> Options:


I had a look at a trunk export from 3CX Standard and another from 3CX Professional
SIP Trunks -> Select Provider -> Export Provider:

There does appear to be an extra field for Transport Rections only on the Professional version i.e.
<field name="TransportRestriction">UDP</field>

This field is missing in the XML file the trunk export I get from our 3CX v16 Standard installation(s).

I have attached a copy of trunk exports taken from 3CX Standard and 3CX Professional (I have removed identifying information such as trunk name and host details), this should demonstrate what I mean.

Can 3CX add this as a feature request/change request with the next patch: ability to set SIP transport mode on trunks for 3CX Standard

 

[cobaltit]

Sounds like you aren't on the latest version. Install Update 4.

 

[JohnS_3CX]

Yup, go ahead and update and you can now control the behavior of the trunk to force UDP via the drop down menu option.

 

[NTQ_SD]

Thanks for the assistance. It looks like this option did become available from ~3CX v16 Update 3 (the affected servers were on v16 update 2. Now updated to v16 update 4.

 

[JohnS_3CX]

You're welcome, let us know how it goes after applying the setting