How a Call is made from PSTN to Mobile:

Joe to PSTN:
	Hello, this is Joe.  I want to talk to Lynn.
PSTN to MSC:  
Hello, I have a call for Lynn.
MSC to all base stations:
	Calling all base stations.  Where is Lynn?
Base station #1:		Base Station #2:	
	Base Station #3:
	Is Lynn here?			Is Lynn here?	
		Is Lynn here?
Lynn to station #1:		
	(loudly) HERE				
	My ESN is 1123445
	My Station Mark is 100 mW
Lynn to station #2:	
	(softly) Here 	
	My ESN is 1123445
	My Station Mark is 100 mW	
Base station #1 to MSC:
	Lynn is HERE and she is THIS loud.
	Her ESN is 1123445
	Her Station Mark is 100 mW
Base station #2 to MSC:
	Lynn is here and she is this loud.
	Her ESN is 1123445
	Her Station Mark is 10 mW
MSC (thinking):
	Hmm… does Lynn’s ESN match my records.  
Yes, it does!  From her ESN, I can find her HLR (home 
location register) and decide how much to bill her and if 
she has any special calling plans or features.
I can bill her 70 cents per minute!
Which base station shall we use?  #1 was louder than #2, I 
can tell that from her station mark.
MSC to base station #1:
	Base station #1, set up a voice channel for Lynn.
Base Station #1 (thinking):
Hmm.. we need a new voice channel for Lynn.  Jeremy just 
finished using 824 MHz.  We will put her there… 
Base Station #1 to Lynn:
	Lynn, please set your frequency to 824 MHz.  
(Lynn’s phone rings.)
Lynn to Base Station #1:
	(Lynn picks up the phone) Ok, frequency set to 824 
MHz.  “Hello?”
Base station #1 to MSC:
	Ok, Lynn is ready to receive voice.  Here is her 
message, “Hello?”
MSC to PSTN:
	Ok, Lynn is ready to receive voice. Here is her 
message, “Hello?”
PSTN to Joe:
	“Hello?”
Joe to PSTN:
	“Hello, Lynn, this is Joe.”
PSTN to MSC:
	Message to Lynn: “Hello, Lynn, this is Joe.”
MSC to Base station #1:
	Message to Lynn: “Hello, Lynn, this is Joe.”
Base station #1 to Lynn:
	Message to Lynn: “Hello, Lynn, this is Joe.”