The reason you cannot switch back and forth between contract and no contract is because of the differences in price. T-Mo understands that people don't like contracts so came out with the no contract option....it is less per month since there is no contract and they cannot offer a discount on the phone because you are free to leave at anytime. For people who like to get new phones on a regular basis or just cant afford to pay hundreds up front just for the phones, they have the contract plans were you pay more monthly but less up front. Depending on the phone you purchase and if you recieve a corporate discount on your monthly bill determines which option is best for the individual. It is actually the best option overall as all other carriers require a 2yr agreement when activating service.

Coverage is realitively the same amongst carriers these days despite the advertisements. The studies that are done are based upon carrier coverage at the customer's home address. Verizon is the highest at 98% of customers and T-mo is now 2nd at 96%.