There are 3 major network providers in Vietnam such as Viettel, Vinaphone and Mobiphone. Viettel is the largest mobile network operator while Vinaphone is the second largest provider and Mobiphone is the third largest provider in Vietnam. If you travel in rural area, Viettel network provider is more preferable.
You will find it easy to get a SIM card at telecommunication stores, booths or even street vendors. However, it is better to find a SIM card at official stores. The official shops will activate the SIM card for you. Prepare passport to register and make sure your phone is unlocked before getting a SIM card. The price for a SIM card is between 90,000 VND (approx. 4USD) – 200,000 VND (8.8 USD) depending on the number.
3G and 4G connections are available in Vietnam. However, 4G connection is new and although it is faster, the availability is said to be unstable (according to a global mobile network report). This article will mention about the 3G connection. For those who stay in Vietnam in a long time and want to use 4G connection, it is better to buy a 4G SIM card at first time.
Each provider has its own package but it is better to take the pre-paid package. Check the balance by typing *101#, validity by typing *102# and top up by typing *100*<PIN code>#. Top up price is from 10.000 VND to 500.000 VND.