Samsung Galaxy S21 5G Bands

2G B2 (1900), B3 (1800), B5 (850), B8 (900)
3G B1 (2100), B2 (1900), B4 (1700/2100), B5 (850), B8 (900)
4G B1 (2100), B2 (1900), B3 (1800), B4 (1700/2100), B5 (850), B7 (2600), B8 (900), B12 (700), B13 (700), B14 (700), B18 (800), B19 (800), B20 (800), B25 (1900), B26 (850), B28 (700), B29 (700), B30 (2300), B38 (2600), B39 (1900), B40 (2300), B41 (2500), B46 (5200), B48 (3800), B66 (1700/2100), B71 (600)
5G N1 (2100), N2 (1900), N3 (1800), N5 (850), N7 (2600), N8 (900), N28 (700), N40 (2300), N41 (2500), N66 (1700), N71 (600), N77 (3700), N78 (3500), N79 (4700), N260 (39GHz), N261 (28GHz)

Coverage in Vietnam

2G B3 (1800)B8 (900)
3G B1 (2100)B2 (1900)
4G B3 (1800)
5G No

Operators of Vietnam

2G 3G 4G 5G
MobiFone B3 (1800)B8 (900) B1 (2100) B3 (1800) No
Viettel Mobile B3 (1800)B8 (900) B1 (2100)B2 (1900) B3 (1800) No
Vinaphone B3 (1800)B8 (900) B1 (2100) B3 (1800) No