3cx softphone provisioning UDP TCP TLS

[daktur]

Hi everyone,

Me again.

What is the difference when using UDP, TCP or TLS when provisioning the 3cx softphone.

Is there any difference if local or remote extension in this case?

Thanks a lot!

 

[sip.bg]

In few words:
Standard implementation uses UDP protocol for SIP and RTP traffic. RTP is responsible for carrying audio. SIP communication carries all information about registration, making and answering calls, caller-ID, call termination, BLF status, etc. This happens on port 5060 normally, while RTP uses ports 9000-9500 typically.
Some phones can use also TCP protocol for SIP, but normally TCP is used when traffic is encrypted, i.e. TLS is used. TLS uses port 5061 normally. Encrypted traffic normally would encrypt also RTP traffic (i.e. Secure RTP or SRTP is used). Encryption is made using installed certificate in 3CX PBX.
3CX phone for Windows may be configured to use encrypted traffic, i.e. TLS and SRTP.
This seems not possible yet for mobile 3CX clients (Android, iOS).

 

[daktur]

@sip.bg ,

Thank you form your explanation. Is there any difference between using insecure TCP or UDP? Are their efficiency anyhow different?

Any of them dispense the RTP?

Thanks again.

 

[sip.bg]

Not all systems (phones, etc. or providers support TCP), so UDP is the commonly used protocol for VoIP. More about the protocols and the difference between them: https://www.howtogeek.com/190014/htg-explains-what-is-the-difference-between-tcp-and-udp/