rsn

To the OP, I've done exactly what you're asking about...with no custom or duty... So I'm only going to address the mailing issues.

The best way to mail is to use U.S. Postal Service either Priority or Express International...

DO NOT use FedEx or DHL or UPS, or you're very likely to get hit with a bunch of costly fees, VAT, duty, handling, etc. etc.

Even though it may be cheaper, for mailing a cell phone, I would NOT use the U.S.P.S. flat rate Priority envelope or small box, even though the phone might fit in them, because they are not trackable.... Regular Priority mail mailings are, but the Priority flat rate envelope and small box are not... Check the U.S.P.S. web site.

If you go U.S.P.S., the package will be delivered in Thailand by the regular mail man.... and more than likely, with no duty or tax at all... especially if it might be a refurbished or already used phone... even if just "used" by you for testing before sending... You're better off if the phone can be considered used by the time you send it.

On the customs form, make sure you classify the package as a gift, not merchandise.

I agree that it would be easier to mail the SIM and then have the MiL purchase GSM900/1800/1900/2100 phone here. e.g. Nokia 3120 Classic. But if you must send the phone/SIM then I'd use USPS PMI Flat-Rate Box ; under 4 lbs $13.45 and declare the contents and value. Or use shipitto. I don't see any way to avoid duty/taxes, although there are many reports that these are sometimes not collected, or are reasonable.

BTW, you should tell your MiL that she should not use her phone in the Immigration Hall when arriving in the U.S. as this is strictly prohibited and the phone can be confiscated, after Immigration, in the baggage claim area it is acceptable.

I agree that it would be easier to mail the SIM and then have the MiL purchase GSM900/1800/1900 phone here. But if you must send the phone/SIM then I'd use USPS PMI Flat-Rate Box ; under 4 lbs $13.45 and declare the contents and value. Or use shipitto. I don't see any way to avoid duty/taxes, although there are many reports that these are sometimes not collected, or are reasonable.

Why not just buy the SIM card and send it. If she already has a phone she can change the SIM card as one person said.

rsn, on 2010-09-26 23:15:04, said:

Perhaps people prefer not to take such a backward approach.

As someone suggested it is much better to send the SIM and have her buy phone in Thailand if she does not already have one.

Another option for most people traveling from Thailand is just use your Thai phone and SIM.  I have used mine roaming to most major countries around the world.  Once I get to my destination and plan on staying a while I then buy local SIM.