The majority of existing GSM positioning techniques can be described as either costly or with limited performance. Basic GSM positioning techniques cell-ID and cell-ID+TA can be upgraded to decrease positioning error. We introduce a new location technique E-CIDTA that requires no additional infrastructure. A probabilistic approach is used to model TA parameters behaviour over distance. These models are applied to the E-CIDTA algorithm to estimate the location of a mobile user. Finally, we evaluate and discuss the performance of E-CIDTA and compare it to other positioning techniques