January 2016
Intermediate to advanced
384 pages
8h 6m
English
book
Building Telephony Systems with OpenSIPS - Second Edition
by Flavio E. Goncalves, Flavio E Goncalves, Bogdan-Andrei Iancu
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Call transfer
To transfer a call between two user agents on SIP requires a lot of coordination. All the devices should support the REFER message and, for attended transfers, the Replaces and Referred-By headers. To explain how a transfer occurs, we will see a scenario where a PSTN user sends a call to the PSTN gateway, and this extension transfers the call to another extension—a typical scenario for an operator. We will see these scenarios for unattended (blind) and attended transfers.
An unattended transfer
Looking at the following call flow, you will notice that the function of the SIP proxy in a call transfer process is simply to relay messages between the gateway and endpoints. You do not need to change anything in the routing script to support ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.