Vietnam's GSM 900/1800 network is compatible with most of Asia, Europe and Australia, but not North America. In Ho Chi Minh City you can buy a local SIM card and minutes for around VND100,000. The most popular providers are Vinaphone, Mobifone and Viettel. For landlines, the city code for Saigon is 08 (drop the 0 if including the country code) and the country code is +84.
When you buy a SIM card you'll get a local HCMC number. You can send text messages worldwide for about VND3,000. A new, no-frills mobile phone can be had for as little as VND400,000, sometimes with credit included in the price. The store will usually set up your phone in your language choice. Take care when pulling out an expensive smart phone on the sidewalk, particulary along busy tourist streets in Saigon's centre, as drive-by phone snatchings are not uncommon.
80 Nguyen Du, District 1; 08 3822 8171
43 Nguyen Cu Trinh, District 1; 08 6655 1206
80 Nguyen Du, District 1; 08 3939 0491