Presence Information using RTC Client API

Hello everybody.

I’m a spanish Computer Sciences studen and I’m doing my Project
I’m making a C# solution using RTC Client API. This solution ill be similar as Windows Messenger (IM, Audio/Video Conference, Contact list, Presence Status, …) and as a SIP server, I’ve to
use Asterisk.
I can register one user and it works without problems, but first, I
tested presence information features (add/remove buddyes, contact
list, presence status, …) in Asterisk using the last version of
Windows Messeger (that is made using RTC and SIP) and although user
registration works fine, presence features doesn’t work (i.e.: I add
one buddy and I can’t see each other).
How can I config my Asterisk? Is possible to add this presence

If you want, I can show you my register code or sip.conf file.

Thanks in advanced and sorry for my english.