[reSIProcate] resiprocate and B2BUA

[Mohammad Farooq <mohammadfarooq@xxxxxxxxxxxxxxxxxx>]

Hi guys,

I am new to SIP and obviously new to resiprocate. I am trying to build a
very simple B2BUA prototype. All this B2BUA does, at start up it
registers with the IP PBX and from there on it receives request from the
PBX and after making some changes to the header fields, it sends it back
to the PBX. 
        B2BUA           IPPBX
          |REGISTER       |
          |-------------->|
          | OK            |
          |<--------------|
           INVITE
          |<--------------|
          |INVITE         | 
          |-------------->|
          |               |
          | So on         |


I would appreciate if someone points me to the right direction and
explain me what tools are available in resiprocate to achieve this
simple task. Any working example will be very helpful.
One more question, what is DUM? Is this a glorify name of an user agent?
Thanks in advance.

Farooq