[Serusers] Call limiting ?

[Alexandre Snarskii]

Hi!

As far as I know, SER does not have functionality of limiting
number of calls on per-user basis. It was discussed years ago,
and the reason for that was "We don't have ability to know is call
still alive" 
(http://lists.iptel.org/pipermail/serusers/2004-November/013035.html)

But, in April 2005, RFC 4028 (Session Timers in SIP) appeared, and
it (at least theoretically) can be utilised to achieve knowlege of active 
dialogs, and, as result - on number of active calls. 

And this RFC looks like supported on Cisco gateways: 

U X.X.X.X:59104 -> X.X.X.X:5060
INVITE sip:aaaaaaa at X.X.X.X:5060 SIP/2.0.
Supported: 100rel,timer,replaces.
                  ^^^^^
Min-SE:  1800.
^^^^^^^^^^^^^^
User-Agent: Cisco-SIPGateway/IOS-12.x.

Question: is this RFC/functionality planned to be supported in SER ? 
If not - are there any good intro on "How to write SER module by yourself" ? :)