Anyone have suggestions on how to the enable the following scenario?  Allow internal but control external per user.

More importantly how to disable or enable PSTN access for a specific user in a domain (profile)?

user1@domain1.com <--> FS <--> Allowed PSTN

user1@domain1.com <--> FS <--> user2@domain1.com

user2@domain1.com <--> FS <--> Not Allowed PSTN

user2@domain1.com <--> FS <--> user1@domain1.com

Thanks,

Roberto