Or better yet, since you saved a bundle buying a used system and you don't want to pay for a service call, pack it up and send it someplace for repair :-)

Don't throw logic out the window when it comes time to figure out why 16 doesn't work. It isn't a mystery, it's a Partner. Check 15 and 17. If they work, try to find out what's different. As far as your 312 goes, I'd have to get out the manual and read the instructions...I believe the term is RTFM... Isn't that the reason you bought the phone system?

Carl

This model is end of life