i maintain my viettel number since i fly often.
as long as sim card balance above 50K VND, upon landing can connect to viettel network
and use SMS to activate 7GB/7Day plan at 30K VND.
"ST30K 395994994" to 9123.
everyday you can sms
"KTTK" to 191 to see how much data you have left.
or
dial *101# to see how much balance you have in the sim card.
not enough for next trip go convenience store buy topup card.
before flying out of vietnam to cancel the plan by
"HUY ST30K" to 191.
reply sms with
"Y" after it ask u to confirm.
else the plan auto-renew every 7 days and deplete ur balance.
for the frequent travelers!
