Vietnam is pretty restrictive as the VC dont like the Internet. You can try an ISP ( like vietnam.net
http://www.vnn.vn/ ) but its proxied in Ha Noi (and I think the same over all of Nam by now). All ports are blocked except www, ftp, telnet and email. Its
very bloody slow 24 hours a day too. The whole country connects to the Net through a few leased lines and the total bloodey bandwidth is only 4MB. And here you need to supply a "fee" to the right people to have the I.S. capability of your account "adjusted" each month). But it still works out relativley cheap compared to connecting internationaly (VND290/min). Its just all the parenoid commie crap you have to put up with.
The best dependable global ISP is what was ibm.net:
http://www.attbusiness.net/ and I usualy connect through HKG up here if Im not in the mood for the local ISP bullsh!t. It works well in SIN too (with no proxies!) Sure all this is an expensive way to log on but necesary.
I recomend carrying a satcom link as the local phone lines can be very unreliable especialy out in the sticks.