What is the difference between B2BUA and proxy in SIP protocol ?

[Bahlul Guliyev]

Dear all,

Can anybody explain me, what is the difference between SIP B2BUA and SIP Proxy?

Best Regards

Bahlul

[Vivek Batra]

Please check this recent discussion;

https://supportforums.cisco.com/discussion/12691841/sip-topolgy

- Vivek

[Ayodeji Okanlawon]

In addition to Vivek's reference..

A SIP B2BUA can both innitiate a request and then at the same time provide a response to requests. A B2BUA combines both the functionality of a UAC and a UAS. A UAC is a user agent client that innitiates a request and a UAS is a user agent server that generates a response to the request.

A proxy server relays requests and responses, A proxy most times just acts as a middle man between the client and the terminating server

[Bahlul Guliyev]

Dear Ayodeji,

Thanks for explanation. 

Best Regards

Bahlul

[thecableguy]

So it sounds like the B2BUA and the Proxy work in conjunction with each other? Would that be an accurate statement?

[Vivek Batra]

Technically they are different. Proxy functionality (stateful and stateless) is defined by RFC 3261, whereas B2BUA which is originated and implemented as a byproduct of advanced requirement and not standard defined.