Hi -

I've got an AT&T iPhone 5 (unlocked), and will be heading overseas (China, Australia, France) on a number of business trips in the coming months, and I'd like to be able to access Google Maps, translate, and so on. Having been burned on AT&T's ridiculous international data charges before, I'm planning to do the following:

1. Sign up for a T-mobile Simple Plan ($50/month with unlimited international texting and data (albeit slow) and 20 cents/minute calls)

2. Swap out the AT&T nano sim card on the iPhone a few days before the trip with the new T-mobile card and make sure everything's working

3. Use the phone overseas more or less like I would at home. Has anyone out there achieved 3G speed overseas?

4. Swap the T-mobile card with the At&T card when I get back home

5. Keep the T-mobile plan active for tethering, international travel and so on.
One question that I have is whether tethering will work overseas, even if it's slow.

6. Repeat steps 2-4 for each international trip.

Does that seem like a workable plan? I've got an old unlocked AT&T iPhone 4, but it's really slow on iOS 7.1.

Thanks in advance for any guidance!