Convert Contact

Vietnam phone number converter is an application supports users in Vietnam with features:
1. Convert phone numbers from 11 to 10 digits
2. Convert cell phone number by region code
3. Show Viettel, Mobiphone, Vinaphone, Vietnam mobile mobile phone numbers
4. Show contacts by province/city 
5. Filter phone number by phone code
6. Show duplicated phone number, name
7. Show no phone number, no name contacts
8. Merged contacts
9. Export contacts
And other useful functions.