Update todo

darcs-hash:20090206122251-58252-765885e6be45a9c4bd9f20c0ead1be044992ab9a
Added TODO to allow ringtone to be settable per session and to generate ring tone using DTMF generator

darcs-hash:20090206123336-58252-039bb3d7ea69f52404f8a2b6c4ce72c73a5b8825