Synchronization is an essential prerequisite for all mobile networks to operate. It is fundamental to data integrity; without it, data will suffer errors and networks can suffer outages. Radio base stations rely on having access to reliable and accurate reference timing signals in order to generate radio signals and maintain frame alignment. Effective synchronization also permits hitless handover of subscriber connections between adjacent radio base stations. The measurement of time interval error (TIE) is a method for evaluating reference timing signals. This article describes the process.