The ‘0’ in a phone number is called a ‘trunk prefix’ – it is used to notify the circuits of the telephone network that the dialed number is in another region of the country.
It is similar in function to a leading ‘1’ used within the North American Numbering Plan (NANP).
- Where a leading ‘0’ is found
- Dialing within the same country/region
- Dialing from outside the country/region
- Mongolia and Hungary
It is found sporadically across African and South American countries.
Hungary uses ’06,’ and Mongolia uses ’01’ or ’02’ as a trunk prefix.
… long distance
When dialing within the same country, the usual rule is to dial a leading ‘0’ when calling long distance or when calling to a different regional code.
Long distance calls are usually billed at a higher rate than calls to local numbers.
Specific dialing rules can change greatly across countries.
When dialing locally (within the same area or geographic code) the general rule is that the leading ‘0’ and the area code are not part of the calling sequence.
Local calls rates are lower (or included in a flat rate) than calls to long distance numbers.
Specific dialing rules can change across countries.
… mobile phones
Some countries have separate area (geographic) codes for mobile phones. Most of them include the leading ‘0’ in the dialing sequence when calling between a mobile phone and a landline.
… it is dropped most of the time
When dialing to a country with a leading ‘0’, most of the time the leading ‘0’ is not included in the call.
If this number was dialed from London, United Kingdom, it would be dialed:
|00||33||1||40 20 53 17|
|exit code from the UK||country code for France||geographic code for Paris||local phone number within Paris|
In this case, drop the leading ‘0’ as it would only be used as a long distance trunk number when calling across France.
… it is modified some of the time for calls to Hungary
International calls to Hungary have a leading ’06’ dropped from the call sequence.
… it is not dropped for calls to Italy, San Marino, Vatican City, the Ivory Coast, Rwanda, and the Republic of the Congo (but not the Democratic Republic of the Congo)
When calling to these countries, include the leading ‘0’ in the call sequence.
Rwanda uses a leading ‘0’ as a designation for satellite phone numbers in the country.
In both these countries, the entire trunk prefix is dropped from the call when calling from outside the country.