The best way to do that is to throw a party and when your friends bring their phones, ask them how their signal is at your house. Have them make a call or two.
For me, the three majors really suck and T-mobile can't get a signal even outside. My neighbors won't allow any towers and since this is a "nicer" neighborhood, they have the political pull to get their way.
So, i had to buy a Wilson repeater.