Unlock iPhone 3GS - Doesn't take ALL SIM cards?

[ntrigue]

I successfully unlocked a [WEEK37] iPhone 3GS for my Dad; he frequently travels overseas. Everything appears to have worked in the US but he recently went to Thailand and could not get service with the SIM he used.

Is this a problem he's going to run into frequently? I suspect I should have turned-off 3G then unlocked as you are supposed to do on T-Mobile. His phone works in the US on AT&T.

Thanks all!

 

[iShater]

If it is unlocked where it can use a Tmo SIM, it should work anywhere. I used mine in Kenya and in Turkey, no problems.

 

[NathanA]

I suspect I should have turned-off 3G then unlocked as you are supposed to do on T-Mobile.

I suspect this. You don't need to do it in that order, mind you. Just remember to turn off 3G in the phone anytime you are going to be using a SIM for a network that doesn't support 3G on the frequencies that the iPhone supports for 3G networking.

-- Nathan

 

[khongaeng]

He probably bought the wrong SIM type

My guess is he bought the wrong type of SIM when he was in Thailand. I know, because I made the same mistake when I traveled to Thailand.

You have to make sure to buy a GSM SIM because they sell two types of SIM cards over there. I can't remember what the other system is.

I believe all the carriers over there have GSM SIM cards available. If he talks to someone who doesn't know what he is talking about, go to the next place (there are at least 10 on every block) and ask for a GSM SIM card, because someone will understand what he needs.

Also, do what Nathan recommends, because having 3G activated on the iPhone with a GSM carrier that doesn't have 3G capabilities will prevent you from connecting to the network

 

[ntrigue]

Thanks all! He's back in the US and using a legit AT&T SIM yet everyone he calls it says, "cannot connect."

 

[iShater]

Thanks all! He's back in the US and using a legit AT&T SIM yet everyone he calls it says, "cannot connect."

Did he try another active SIM?

 

[ntrigue]

Did he try another active SIM?

I had him Reset Network Settings. Worked!