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[SOLVED] how handset detects the operator

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Feb 23, 2013
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I got this doubt when I am studying about mobile technologies. " How mobile handset will detect the operator when you change your sim. As each operator has his own frequency then how handset will able switch immediately having only one duplex antenna."

Thanks in advance

As each operator has his own frequency
This is only true in some cases and when they do, they are usually very closely spaced within the same band. The main distinction between them is the ID in the data stream.

"AT+COPS" will normally tell which operator is in use.

first of all thanks for replying.

Who will send the command each time when you change yur sim will it be your handset processor or processor lied in SIM. As i gone through some of the presentations I found that there separate transceivers for GSM and 3g. Also an antennae switch. By observing those I Understood that the DSP will switch the antenna via antenna switch ic.
Am I correct in this scenario. Please clarify me.

Most if not all SIM cards are just non-volatile RAM. The processor in the handset will be alerted to the SIM change, either by a mechanical switch or noticing the change in card contents. This will prompt it to send the command to search for the network provider.

The antenna switching process varies from one country to another, in most cases GSM and 3G share the same band but 4G is on a different group of frequencies. There may be different antenna for each band but it's generally easier to make a single antenna that resonates on all the frequencies being used.


Thanks for that. Its very useful for me. I am eager to know more things about technology.

Thanks once again for spending your valuable time

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