Cellular Network (Simplified)
A mobile phone places a call by sending a call initiation request to its nearest base station. This contains a unique identifier - The International Mobile Equipment Identity (IMEI). The base station sends the request, which contains the telephone number dialled and the IMEI, to the mobile switching centre (MSC)
The MSc validates the request:
Is there enough credit?
Can the user make the call (no call bar) ?
And if allowed, makes a connection to the number called via the public switched telephone network (PST)The steps that take place when a mobile station receives an incoming call are as follows
The mobile phone, when switched on, informs the MSC that…