How SIP hold using RFC6336 is implemented and how it looks in production.
Tag Archives: RFC3261
SIP Supported & Require
Function of Supported & Require headers in SIP.
SIP Route, Contact, From Headers – Which to use?
The rules for which headers to use when creating a SIP request and knowing where to route it.
What is a SIP Registrar?
Explanation of what a SIP Registrar does, Contact header and Address on Record, and how it all fits together to route messages correctly.
SIP Concepts – Record Routing
Explanation of Record-Routing, why it exists and how it’s used.
Why z9hG4bK?
Why does every SIP branch start with z9hG4bK?
Reverse MD5 on SIP Auth
How the SIP Authentication mechanism works, and how we can reverse it to check the password we’re expecting is the encrypted value we’re seeing in captures.