A single cell in an analog system uses one-seventh of the available duplex channels. This means that each cell is capable of handling 56 voice channels. Digital methods, however, allow three times as the number of voice channels. This is explained later. Therefore, two or more non-adjacent hexagonal cells can reuse the same 56 or more frequencies.
Most cell phones are battery-operated.
Their power consumption is very low and that means small batteries. That's what makes mobile phones mobile. This office handles all phone connections directed to the normal land-based phone system. All cell phones have special codes associated with them. The ESN is a permanent part of the phone.