When phoning a certain Thai mobile number I get the answer "there is no signal".

Does that that mean that the person has removed the sim card from the phone ?

It probably means their phone is turned off or out of range.

Thanks, well, it is possible that this person has gone to China on business.

or they dont want to talk to you

or they dont want to talk to you

Yes, that's the question. Have they changed to a new number by putting in a new sim card or are they out of range ?

I hoped to be able to figure that one out,by listening to the answer I get when I phone. But I suppose that is not possible.

Or their battery is flat.