Cell-ID operates in most types of cellular networks, including GSM, GPRS, and UMTS/HSDPA networks. It is the simplest way to describe the general location of a handset. It requires the network to identify the Base Transceiver Station (BTS; essentially the cell tower to which the device is connected at the time) to which the cell phone is communicating and the location of that BTS. If this information is available, the Location Server identifies the device location as being the location of the base station and passes this information on to the location service application.
Since the MS can be anywhere in the cell, the accuracy of this method depends on the cell size and can be very poor in many cases, because the typical GSM cell is anywhere from 2km to 20km in diameter. Thus Cell ID positioning is generally more accurate in urban areas with a dense network of smaller cells than in rural areas where there are fewer base stations. Ultimately, the diversity in cell-site size, density and operational characteristics across a network makes the accuracy of this technology inconsistent.
Generally, the yield and Time To First Fix (TTFF) of Cell ID are very good, but the accuracy is poor and the consistency of the solution varies dramatically, depending on cell site density. It is particularly poor in rural areas where cells are a long distance apart. In terms of implementation, it supports roaming to other networks without major modifications, is easy to maintain, and requires no major cost expenditure to expand the network. Despite these advantages, the basic accuracy performance supports only the minimum of possible services.