Wow, where do you live that makes ATT signal not available ???The first time I tried to set it up - at the dealership on the day I picked-up the car - we had that problem. I think we eventually rebooted the system for a "factory reset". I recall that I needed to reboot my phone several times, as well... It was 6 months ago, though, and I so rarely use the app (this area has nearly no ATT signal, Honda's system-of-choice) that I've kind of dismissed it from my mind...
I would be a bit peeved if I had the app features and could not use it.