So so system.
Once in a while I have to either delete the software and redownload it to my iPad Air 4 and other times reboot the iPad. That because I miss calls and text message. Sometimes I get to see that I got a call or a text message only much later and I do mean much later. Furthemore, long text message that take moré than one line cannot be reread after they are sent, that is part of the lines are hiden and it is impossible to move the text to one side or the other in order to remember what was written. Added to this is when the line cuts off during a phone call for some unexplainable reason and try to phone back, I have to reboot other wise the app indicates that i'm already in line with the other party. So yes I can't give more than three stars. I am even tempted to give a 2 star rating. Yet the phone line service is adequate, thus 3* !