P.Schuman wrote:
> Which types of phones have SIM cards ?
> I recall that initially the GSM phones had them,
> but don't know if they have also become mainstream
> for a lot more phones that are not on GSM networks ?

Only GSM phones have SIM cards. iDEN phones have a "RUIM" card that
looks like a SIM card. Once upon a time, CDMA phones were going to get
RUIM cards but it didn't happen.
>
> I friend travelled to Egypt, and said he "bought" a SIM with prepaid calls,

You do that in the US and in Europe, too.

> and loaded it onto his phone, and then used his normal SIM the rest of the
> time ??
> How did he do that.... did the prepay SIM get "copied" to some internal area
> ?

It's just as easy as it sounds. Nothing special happens.

>
> What happens when you move a SIM from phone to phone ?
>

If I put your SIM in my phone - I have your telephone number and phonebook.


> Another friend just upgraded to a new BB on Sprint (I think),
> and when he was at BestBuy, the clerk "pocketed" the old SIM,
> until my friend caught him, and demanded the SIM be put back into the new
> BB.

Sprint does not use SIM cards. When an old number is moved to a new SIM,
the old SIM is jewelry, I think. Someone will correct me, I'm sure.
Regards