How to get international dialing code on iPhone?

I know i can get the country code with NSLocaleCountryCode but I'm looking for the numerical equivalent to generate an internationnal phone number.

I need 01 instead 开发者_JS百科of US.

I can of course use my own table but I'm guessing there is already an API for that but I can't find it.

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I'm pretty sure there is no such thing in the iPhone SDK.