Long distance card providers

Hi group.
I will be visiting Vietnam in few weeks and would like to know any provider for cell phone, that I can buy a chip and charge it with 3 months package? I will need to be able to whatssap and text at least internationally. What cell phone carrier is the best for this? and how much should it cost.
Thanks  a lot

I've been looking for the same information.
I checked my city of interest and found the predominant company.
I chatted with a rep and quickly found my Viet language skills taxed severely.

Viettel Mobile (directly under Viettel Corp. ...
MobiFone (directly under VMS): 090, 093, 0120, 0121, 0122, 0126, 0128.
VinaPhone (directly under VNPT): 088 (New number from 2017), 091, 094, 0123, 0125, 0127, 0129.
S-Fone (directly under CDMA S-Telecom): 095.
Vietnamobile (ex-HT Mobile): 092, 0188.

Jim-Minh wrote:

S-Fone (directly under CDMA S-Telecom): 095.


Has S-Fone risen from the dead?  :unsure
https://thanhnien.vn/tai-chinh-kinh-doa … 61027.html
https://www.vir.com.vn/vnpt-divests-ent … 59082.html