HI Group, I run into a wired problem. It is a MICS 6.1. It has happened to reception lots of time when she was on an intercom call with other staffs, the calls dropped. Sometimes, when she calls those extensions, she hear one ring back tone and the call stops. On the screen of the reception phone, it shows Not In Service. She then tries the same extension. It will work again. This happens randomly when reception calls other extensions. They never had any problems with outside calls. I am considering replacing the power supply. Has anyone experienced problem like this? Or other than the power supply, could it be the software issue too?