Tips: Iphone4s - Field Test Mode
Field test mode is available in iPhone 4s iso5, Which will allow easy and precisely test your cell signal reception quality. Your signal bars will be replaced with a number like -85. The closer to 0 you are the stronger the signal is. Ok open up you phone and goto the dial pad then type in the following sequence and press call
Side note: this has to be done from the dial pad will not work from a stored contact.