081 is not a country code. Numbers inside a country start like this: AIS (Thailand), Chur (Switzerland), Abreu e Lima - PE (Brazil). The first digit 0 is the trunk prefix for domestic calls and is dropped from abroad.
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| Area or operator | From abroad | Inside the country |
|---|---|---|
 AIS · Thailand | +66 81 … | 081 … |
| DTAC · Thailand | +66 81 … | 081 … |
| TOT Mobile · Thailand | +66 81 … | 081 … |
| 1 more in Thailand | ||
 Chur · Switzerland | +41 81 … | 081 … |
 Abreu e Lima - PE · Brazil | +55 81 … | 081 … |
| Agrestina - PE · Brazil | +55 81 … | 081 … |
| Aldeia - PE · Brazil | +55 81 … | 081 … |
| 72 more in Brazil | ||
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.