0251 is not a country code. Numbers inside a country start like this: Donduseni (Moldova), Münster (Germany), Kalyan, Maharashtra (India), Beverwijk (Netherlands) and others. The first digit 0 is the trunk prefix for domestic calls and is dropped from abroad.
Have the full number? Check it in the number lookup.
| Area or operator | From abroad | Inside the country |
|---|---|---|
 Donduseni · Moldova | +373 251 … | 0251 … |
 Münster · Germany | +49 251 … | 0251 … |
 Kalyan, Maharashtra · India | +91 251 … | 0251 … |
 Beverwijk · Netherlands | +31 251 … | 0251 … |
 Bogor · Indonesia | +62 251 … | 0251 … |
 Dolj · Romania | +40 251 … | 0251 … |
 Älvdalen · Sweden | +46 251 … | 0251 … |
 Lara/Yaracuy · Venezuela | +58 251 … | 0251 … |
 Dong Nai Province · Vietnam | +84 251 … | 0251 … |
If a number starts with +, the first 1–3 digits are the country code. If it starts with 0 (8 in Russia and Kazakhstan), it is a domestic number: an area or operator code follows, and from abroad the 0 or 8 is replaced with + and the country code. The same digits can mean different places, so where the call came from matters.