GSM Location Update Message Sequence Charts

Have you ever wondered how your cellular provider is able to route calls to you virtually anywhere? How does the cellular provider know where you are?

The short answer to these questions is that your cell phone keeps the cellular operator informed about your location.

In the following message sequence charts we will examine how a mobile phones keep selecting the best cell to service your call and also keeps the cellular provider informed about your location.

We will be tracing the journey of a mobile phone from Rockville, Maryland to Vienna, Virginia. The path taken by the mobile phone is described in the GSM Network Example.