Well, there are basically 3 options, that would apply to most BlackBerry users:
- International Roaming
Provided you have international roaming activated on your number, as far as I know the BlackBerry service will work. But be prepared for an enormous bill.
- Use the service over WiFi
Free WiFi is pretty much available anywhere around HCMC (and I hear, in many other cities) - cafes, restaurants and hotels usually provide it free and most of the time, all you just need to ask for a password. The video below will show you how (video by Crackberry).
- Use a local operator
There are now officially two local operators in Vietnam that run the BlackBerry service. Viettel has actually had the service for a few years, but only for BlackBerry Enterprise Server users, and they only launched Blackberry Internet Server available for prepaid cards in August 2011. Mobifone just launched their Blackberry services in December 2011. Now for most users, the BIS plan for prepaid cards would be the most reasonable choice.
How to activate BlackBerry Internet Service on Viettel
For full BIS service, just send BB MAIL TUAN (weekly charging, 30,000 VND/week) or BB MAIL THANG (monthly charging, 100,000 VND/month) to 1602. If you want to see what other service options they have, you can look at Viettel's Blackberry page here, and going to the "Dich Vu" section. Unfortunately the site doesn't have an English service, but you should be able to figure it out.
How to activate BlackBerry Internet Service on Mobifone
For full BIS service, send DK BAS (monthly charging, 99,000 VND/month) or DK BASP (monthly charging, 130,000 VND, comes with 300 MB bonus data) to 999. If you want to see what other service options they have, you can look here. Luckily they have an English section.
Personally I've only been using the Viettel service, and it should be cheaper as they have a weekly charging option, ideal for those who only stay for a few days but simply can't resist getting their Crackberry fix. As a comparison, standard mobile internet packages are much cheaper compared to their BlackBerry counterparts - I used to use a standard phone with a mobile internet package that gave me 350 MB/month bonus for 50,000 VND; and if you can resist the urge to immediately share pictures to Twitter or Facebook, using the WiFi option is usually adequate.