Many phones feature a signal strength indicator, which shows the strength of the signal coming from the nearby wireless transmitter. You can make a call from almost anywhere as long as the transmitter signals from the phone and carrier are strong enough. Remember, you won't hear a dial tone before you place your call. Including the size and quality of the coverage area, customer service, and the quality and diversity of products. Low price does not guarantee best overall value.
More cell sites mean clearer calls.
Typically, wireless subscribers pay a flat monthly service charge, which may include a set amount of air time, and then a certain amount per minute over that time. Therefore, the cost of an individual call depends on the length of the call and the number of free minutes provided in the monthly service plan. When you travel outside this area, your calls are automatically transferred to the cell sites owned and maintained by a different wireless provider. This is usually done at an additional per minute cost, and not covered by your service plan's monthly pool of minutes. Roaming can be expensive.