0906 is not a country code. Numbers inside a country start like this: Donauwörth (Germany), Aletai, Xinjiang (China), MTN (Nigeria), Globe (Philippines) and others. 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 |
|---|---|---|
 Donauwörth · Germany | +49 906 … | 0906 … |
 Aletai, Xinjiang · China | +86 906 … | 0906 … |
 MTN · Nigeria | +234 906 … | 0906 … |
 Globe · Philippines | +63 906 … | 0906 … |
 Orange · Slovakia | +421 906 … | 0906 … |
 FarEasTone · Taiwan | +886 906 … | 0906 … |
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.