817 is not a country code. Numbers inside a country start like this: Minsk (Belarus). The first digit 8 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 |
|---|---|---|
 Minsk · Belarus | +375 17 … | 817 … |
| Area or operator | From abroad | Inside the country |
|---|---|---|
 Vologda · Russia | +7 817 … | 8817 … |
 Aledo, TX · United States | +1 817 … | 1817 … |
| Alvarado, TX · United States | +1 817 … | 1817 … |
| Arlington, TX · United States | +1 817 … | 1817 … |
| 19 more in United States | ||
 Nanchong, Sichuan · China | +86 817 … | 0817 … |
 XL · Indonesia | +62 817 … | 0817 … |
 9mobile · Nigeria | +234 817 … | 0817 … |
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.