Handsets register with TCP

[hood]

Hi All,

I have a client that is having some issues with registration on some handsets that register to the 3CX PBX via a different subnet passing though a firewall device.

A 3rd party has been doing some investigation, and has asked if the 3CX system and phones could be changed to use TCP rather than UDP.

Is this possible, I cannot see anywhere obvious to make the change.

Thanks in advance.

 

[manfer]

SIP can work via TCP or UDP. RTP can only work via UDP protocol.

Look at the ports used by 3CX
https://www.3cx.com/docs/3cx-phone-system-v14-ports/
and you can see that SIP port 5060 is TCP&UDP, while the RTP ports 9000-9500 are UDP only.

You have to configure nothing on 3CX system to use SIP via TCP. It will already be listening on both TCP and UDP 5060 ports.

That's something you have to configure on the device, on the voip phone you are using. If you provision it from 3CX you probably have to edit the phone provisioning template as by default all templates are for sure configured to use UDP as SIP transport protocol.