I have had several occasions to talk to MH tech people and they have been pleasant, helpful, and mostly knowledgeable. I bought the duo system feeling that it was best to have two communication devices. To me the base station is a backup; I carry the mobile all the time. Even with only one bar of AT&T signal strength the base station has worked properly. The mobile unit is a different story. I was originally sent a model 3 (tied to 3g network). It would only hold a charge for a few hours. MH replaced it with the newer model 4 (works with 4g networks). What a disaster! The red charging light did not work so you were never sure it was charged. There is a test button on the side which I pressed. The unit reported that the test had failed, but, unknown to me, the call went to the emergency system, calling EMT and my calling list. Within minutes an ambulance, my terrified daughter, and a neighbor showed up. Tech supports tests showed the unit would not receive any signal. One of their people admitted they had some "glitches" in the model 4. In my opinion there is a LOT of work to be done on it before it is released to any customer.These are life saving devices, not toys.. MH again replaced the unit with the model 3,which has worked properly and without problem.. Aside from operational problems with the 4 I like the model 3 best. The GPS light blinks when ever there is a connection, but only lights on the 4 when the emergency button is pressed. You don't really if there is a connection until it is needed and you hope it is there. The 3 also has a mini-usb port that allows charging from a computer when not near the charging cradle. I have stayed with MH because I think they are a good company with good people and their equipment is now all working properly. But they have a lot of work to do in preparation for the dropping of 3g in the next couple of years.