I have a MICS R6 with pri and a nam r7. The customer says that sometimes they here the phone ringing in a strange fashion, then when they pick up nobody is there but caller keeps hearing it ring. this happens periodically on different DIDs. I tried making test calls myself if it worked each time. I've witnessed it happen though. Another problem I'm having is the nam keeps going out and having to be restarted. Do I have power issue? Has any experienced these issues.. Any help pleasssse