is there any way to distinguish between internal and external calls as far as the way the phone rings? is it possible to eliminate the ringing completely on external calls only? we are on rel. 22. my boss is bombarded with sales calls and is looking for some kind of solution so that he will know when internal calls are coming in but won't always be bothered with external calls. we are also about to upgrade to 25.40. if there's nothing available on 22 will there be anything available on 25.40? thank you very much.