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SIP: Does all the SIP control messages passes through SIP proxy-server or only a subset of SIP messages?

+1 vote

In one of the articles it was mentioned "BYE" SIP message routes end to end and by pass the SIP proxy server. What is it mean ? and when SIP proxy servers release the resources that was reserved during the session establishment ?

posted Aug 14, 2016 by Vikram Singh

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2 Answers

+1 vote

During establishment of a dialog between two user agents, multiple proxy server may involve. But once the session/dialog establishes between end user agents, SIP signalling messages can be forwarded directly.
For example : There are two user agents named UA1 and UA2 and UA1 sends INVITE message to UA2. In a typical case, this INVITE message reaches from UA1 to UA2 by using proxy servers PS1, PS2, PS3 and PS4. UA1 has connection with PS1 and UA2 has connection with PS4. After establishing a dialog between these two user agents, message will follow the following path:
U1 <--------> PS1 <--------------> PS4 <-------------------> UA2

ACK, one of the SIP message uses the above path.

answer Aug 17, 2016 by Harshita
0 votes


answer Aug 25, 2016 by Jitendra Jain
Will you like to describe more about your answer?
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