Create a connector to enable one to call buddy via skype. User can update their skype info if/as needed and expose it via location info. Consider as an option below the phone icon (Sametime call, Skype call) when info is available.
create an option to have an SMS relay service (as part of the STGW?) that enables someone to send from their listed (directory or location set) number a SMS msg to the intended/selected buddy's mobile number defined in directory or location awareness settings.