I am currently in Las Vegas. My buddy's phone connects to AT&T and has great service, never less than 3 bars, including in my hotel room. My phone only grabs T-Mobile which has terrible service, constantly dropping out, no service ever in my Flamingo hotel room, only reiable place is walking on the strip. I have a Samsung Galaxy S5 phone. Is some setting preventing my phone from finding a different carrier when T-Mobile drops out? Please help. it would be nice to be able to make calls from my hotel room.