We are a medium size office with many Nortel phone set up on a Norstar network. Currently, we are using the T7316 model phone. The issue that I am having is with several of the office extensions. When our main phone line rings, some of the extensions also ring. This makes it impossible to know when my extension is actually ringing and when the main line is ringing. I wondered if anyone knows how to reprogram the phones so that the extensions ring only when they are directly dialed (through the phone system) from an outside line.