A system and method for estimating a location of a wireless device receiving signals from plural nodes of a Universal Mobile Telecommunications System (“UMTS”) network. Observed time difference of arrival (“OTDOA”) measurements of signals received by the wireless device are collected and a message is transmitted to a stand alone serving mobile location center (“SAS”), the message including round trip time information, tipping information, and the collected OTDOA measurements. One or more location measurement units (“LMU”) are tasked to determine uplink and downlink signal measurements between the wireless device and ones of the plural nodes as a function of the transmitted message. At the one or more LMUs, range measurements from the wireless device to ones of the plural nodes, uplink time of arrival (“TOA”) measurements, and downlink TOA measurements are determined. A location of the wireless device may then be determined as a function of the uplink and downlink TOA measurements, OTDOA measurements, round trip time information, and range measurements.