Diane is going to be traveling to Switzerland and wants to be able to use her phone and tablets locally. Leo says since she uses AT&T's service, she can request that they unlock her phone for the trip so she can buy a local SIM. She's also going to three other countries, and that will cause issues as well.
Leo advises using Wi-Fi whenever possible. She can buy 800MB of international data roaming for $120 and just turn off data when she's not using or needing it. The HuaWei E5331 Mobile Travel Hotspot MiFi device is a good solution and it's offered in Switzerland, where Diane is going. Does she need to get a subscription? Leo says it'll probably come with a data plan. She can buy online, or reserve one on the Swisscom website and pick it up when she gets there.
If she wants to keep her number, she'll have to pay for International data roaming, which is overpriced. Slower EDGE access is free for TMobile customers. Or, since she has a world phone, she can get a local SIM and find information on what's best at PrePaidwithdata. This is a great Wiki that tells what the best carrier is for every country.
In the chatroom, they say that the WaWei MiFi isn't locked. Leo has used one and it's the most affordable and convenient way to use data while traveling.