The parameter in GSM is called "Timing Advance". [http://www.qtc.jp/3GPP/Specs/GSM_GERAN/0510-8c0.pdf http://www.qtc.jp/3GPP/Specs/GSM_GERAN/0510-8c0.pdf] and i

The parameter in GSM is called "Timing Advance". [http://www.qtc.jp/3GPP/Specs/GSM_GERAN/0510-8c0.pdf http://www.qtc.jp/3GPP/Specs/GSM_GERAN/0510-8c0.pdf] and it's the length of time by which the mobile advances its transmission to the base station. So with increasing "timing advance", the mobile has to start transmitting earlier. Units are GSM symbol periods, defined to be 48/13 µs = 3.69µs, which, multiplied by the speed of light (3⋅10^8 m/s) is 1108m. As the distance contributes in both ways (from base-station to handset, and back) one timing advance step is half the distance: about 550m. The base station measures the relative phase of received transmissions from the mobile and will send information to the mobile to set or adjust the timing advance. [look for "timing advance" in http://www.etsi.org/deliver/etsi_gts/04/0408/05.03.00_60/gsmts_0408v050300p.pdf http://www.etsi.org/deliver/etsi_gts/04/0408/05.03.00_60/gsm... which specifies the information elements that are exchanged.] So, yes, it should be possible to get TA for each cell the mobile exchanges data with from the phone.