Juan,
The datasheet and the IOS documentation is the right place to find the details on what RFC standards are supported in the IOS that runs on the 1941. You should make sure to look based on the specific IOS image that is running. For example, the 1941 does not support IOS based voice, as such no H323 or SIP voice standards are supported.
Regards,
Darryl Sladden
Technical Marketing Manager