Botswana:
18 years of age; universal
Brazil:
voluntary between 16 and 18 years of age and over 70;
compulsory over 18 and under 70 years of age
British Virgin Islands:
18 years of age; universal
Brunei:
none
Bulgaria:
18 years of age; universal
Burkina Faso:
universal
Burma:
18 years of age; universal
Burundi:
NA years of age; universal adult
Cambodia:
18 years of age; universal
Cameroon:
20 years of age; universal