Like AJ points out, indoor coverage is highly variable by carrier. In my area, AT&T has the best geographic coverage. However, inside my house I have a full signal on Verizon 3G & LTE, Sprint 3G and T-Mobile EDGE, but I get no AT&T service unless I am outside.
No carrier guarantees indoor service. It depends on how far you are from each carrier's site, which technology/frequencies used and most importantly, what type of construction used for your building.
The best thing to do is to try out each carrier in your home until you find the one that best meets your indoor needs, should in home service be paramount to you. Otherwise, you can get an Airave.
Robert via Nexus 7 with Tapatalk HD