GSM, GPRS, 3G, 4G (LTE), etc.. is built around signalling and State/Entity
Functions. As a result of a request an entity will move from one
state to another in a well defined sequence. In order for this to happen
timers must be used and supported. 3GPP has a lot of specified Timers that are required
for the system to work in a well co-ordinated manner.
Some example of GSM Timers
– Call Setup – T3120, T3126, T3101, T3230, T310, T11, T10, T313, T3107
– Call Clearing – T13, T3111, T3109, T3110
– Handover – T3103, T8, T7, TQHO, T3121
– GPRS – T3182, T3164, T3198, T3180, T3190, T3192, T3312, T3314, T3321
– Miscellaneous – T3210, T3128, T3211, T3212, T3220
Look at the extensive signalling that GSM, etc.. supports. This works because of the
defined timers used for the supported messages.
VBR/ Wallis Dudhnath