I have a friend who has a Nextel i830, which has no international capability. I have an old i2000+ phone that does have GSM capability. Is there any chance that putting the i830 SIM card into the old i2000+ will damage it?

Nextel sells an international only phone that is listed as definitely being compatible, but they want $200 for it, which is stupid.

No, it will not damage it. Though, if the phone is locked by the service provider and you try to use someone else's SIM, it will not accept it.

Only GSM phones have SIMs, of course.

Nextel uses a technology called iDen, not GSM. No SIM cards, so far as I know.

As a fellow Nextel user who is looking to upgrade thier phone, I can tell you that I am 99% sure that the SIM cards in the i830 you have can only be interchanged with other 3 number series phones (i.e. i530, i830, etc.). I remember this from calling Nextel and asking what I would do if I bought a i860 off of ebay -- if I could just switch the SIM card or not....

iDen is a solution, much like PCS was to be a solution. Yes, they do use SIM cards, in probably at least most of the phones. Certainly all the ones I have used in the past five years.

As for SIM cards, I THINK there IS an issue with some carriers and SIM's. For example, some carriers are moving now to a 64Kb SIM, whereas they have been using and others continue to use 32Kb SIM's. I have read over on Hofo, that some people getting 64Kb SIM's have trouble using a phone/carrier combination looking for a 32Kb SIM.

And, the other way around, a phone/carrier looking for a 32Kb SIM can have memory addressing problems if the carrier tries to address 64Kb.

Now, I think the problems were related to killing the SIM, but not damaging the phone, but don't know.

Normally, going from say an UNLOCKED ATT or CINGULAR GSM phone, to europe or asis, and putting in a locally purchased SIM, you are not going to have a problem.

Although, CINGULAR is moving to the 64Kb SIM with some phones now.

I went ahead and tried it out - putting the i830 SIM card in the i2000+. Worked fine - the phone powered up, was authenticated on the network and was able to make calls. At least domestically. I assume it will work internationally, as well.

I don't know what phone you have now, but I wouldn't try switching "up" from an old phone to a new one with the old SIM card. The older cards have a much smaller memory capacity, so you wouldn't want to use that on a day-to-day.

For short-term international travel, I think the i830 -> to i2000+ move is fine.

I was thinking of getting the i930 when it came out, as it does international as well, but now that Sprint is planning to shut down Nextel, I'll wait and see what happens.