I originally heard this story back in July and I figured I'd post a topic about it. Cellphone companies have to ensure that people can use their service in their homes, but many newer homes have great roofing insulation.. so good that it blocks RF signals aka cellphone service as a side effect. So the cellphone companies made a product called a femtocell to give people in blackout areas or low signal areas full cellphone service. My brother had one of these when he was using Sprint. It connected to his high speed internet and he got a much better signal. These femtocells can be bought in electronic stores and online.. The range on these are small.. If someone is going to spy on you, it'll most likely be a neighbor in an apartment building where more people could be affected. Your phone will not show any roaming bars or give you any notification that you are on a femtocell (some might give you a double dial tone but only when making a call, not receiving one).. the phone will look like its on a regular connection and you will never know if someone is reading all your texts or recording your calls.
Now think about how easily the police or NSA can listen in..