0451 is not a country code. Numbers inside a country start like this: Lübeck (Germany), Harbin, Heilongjiang (China), Dindigul, Tamil Nadu (India), Vodafone (Australia) 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 |
|---|---|---|
 Lübeck · Germany | +49 451 … | 0451 … |
 Harbin, Heilongjiang · China | +86 451 … | 0451 … |
 Dindigul, Tamil Nadu · India | +91 451 … | 0451 … |
 Vodafone · Australia | +61 451 … | 0451 … |
 Jhinaidah/Horinakunda · Bangladesh | +880 451 … | 0451 … |
 DIGI Communications · Belgium | +32 451 … | 0451 … |
 Palu · Indonesia | +62 451 … | 0451 … |
 Colonia Volendam · Paraguay | +595 451 … | 0451 … |
 Hässleholm · Sweden | +46 451 … | 0451 … |
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.