we have CM 9.1.1A and 6945 phones. once in a while the customer complains that when they pick up phone and dial, they hear dial tone, then silence until someone picks up call - no ringback. this happens on all calls, extension to extension, etc.
sometimes, a phone will do this continuously until we rest power to phone, then it is ok. other times the phone just begins working ok on its own.
any ideas as to what could be the cause? already upgraded phone to latest firmare ES2, still no go.
phil
