[OpenSIPS-Devel] [NEW]B2BUA in OpenSIPS

[Anca Vamanu]

Hi,

A new feature has been added to OpenSIPS: a signaling B2BUA 
implementation. This implementation gives OpenSIPS power over the calls 
and makes possible building some PBX specific services. It is not a full 
B2BUA as it does not handle media, but only creates and controls media 
sessions.

B2BUA in OpenSIPS is an implementation of the behavior of a B2BUA as 
defined in RFC 3261 that offers the possibility to build certain 
services on top of it. It consists of two modules:

    *

      b2b_entities - the bottom half, implementing the behavior of UAC
      and UAS (B2BUA)

    *

      b2b_logic - the upper half, implementing a logic for analyzing and
      applying services scenarios to achieve the desired B2BUA specific
      services.

The reason for which the architecture has two parts is to allow 
extensions and integration with other system that might implement their 
own logic interpretor. Instead of the b2b_logic module, another module 
with a different logic interpretor or scenario source can be added and 
use the interface that the b2b_entities module offers to build quickly a 
new B2BUA implementation. The b2b_entities role in the processing is an 
independent one that is required in any B2B implementation and it is 
therefore encoded in a separate module. It offer an upper level library 
that will make the implementation of another logic interpreter and 
applier much easier.

The services are defined in *scenario documents* that are XML documents 
with a structure that allows describing many services described in 
detail here http://www.opensips.org/Resources/B2buaTutorial#toc7.

There are two means to trigger a B2BUA service:

    *

      when a SIP message is received, by calling a function from the script

    *

      by sending an MI command

When a certain service should be initiated is left at the decision of 
the administrator.

In the documentation page you can find two services examples with their 
corresponding scenario documents

    *

      *Prepaid* <http://www.opensips.org/Resources/B2buaTutorial#toc12>
      <http://www.opensips.org/Resources/B2buaTutorial#toc12> service --
      triggered from the script.

    *

      *Marketing*
      <http://www.opensips.org/Resources/B2buaTutorial#toc13> service --
      triggered with an MI command.

Other services can also be defined as long as the document format 
permits describing the needed actions. This implementation is only an 
initial version and it can be extended to support other services 
definitions if they will be requested for.

We hope that this will be an useful feature and look forward to hear 
your feedback.

You can read more here http://www.opensips.org/Resources/B2buaTutorial.
Also you can check out the modules documentation: 
http://www.opensips.org/html/docs/modules/devel/b2b_entities.html and 
http://www.opensips.org/html/docs/modules/devel/b2b_logic.html.


Regards,
Anca


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