0387 is not a country code. Numbers inside a country start like this: Švenčionys (Lithuania), Cakran/Frakull, Fier (Albania), Salta, Salta (Argentina), Waingapu/Waikabubak (Indonesia). 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 |
|---|---|---|
 Švenčionys · Lithuania | +370 387 … | 0387 … |
 Cakran/Frakull, Fier · Albania | +355 387 … | 0387 … |
 Salta, Salta · Argentina | +54 387 … | 0387 … |
 Waingapu/Waikabubak · Indonesia | +62 387 … | 0387 … |
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.