Question

In your own frame of words discuss a Call from Mobile to PSTN and vice versa.

Answer 1

ANSWER:-

PSTN to Mobile Phone - At the point when a PSTN subscriber calls a mobile station, the following succession of events happens:

1.The Gateway MSC receives the call and queries the HLR for the information needed to route the call to the serving MSC/VLR.

2.The GMSC routes the call to the MSC/VLR.

3.The MSC checks the VLR for the location area of the MS.

4.The MSC contacts the MS via the BSC through a broadcast message, that is, through a paging request.

5.The MS responds to the page request.

6.The BSC allocates a traffic channel and sends a message to the MS to tune to the channel. The MS generates a ringing signal and, after the subscriber answers, the speech connection is established.

7.Handover, whenever required, happens, as discussed in the earlier case.

Mobile Phone to Public Switched Telephone Network (PSTN) -At the point when a mobile subscriber makes a call to a PSTN telephone subscriber, the accompanying sequence of events happens:

1.The MSC/VLR receives the message of a call request.

2.The MSC/VLR checks if the mobile station is authorized to access the network. Assuming this is the case,the mobile station is activated. If the mobile station is not authorized, then the service will be denied.

3.MSC/VLR analyzes the number and initiates a call setup with the PSTN.

4.MSC/VLR asks the corresponding BSC to allocate a traffic channel (a radio channel and a time slot).

5.The BSC allocates the traffic channel and passes the information to the mobile station.

6.The called party answers the call and the conversation takes place.

7.The mobile station keeps on taking measurements of the radio channels in the present cell and the neighbouring cells and passes the information to the BSC. The BSC chooses if a handover is required. Provided that this is true, another traffic channel is allocated to the mobile station and the handover happens.On the off chance that handover isn't needed, the mobile station keeps on transmit in a similar recurrence.

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