What is the max and min digits for an international telephone number? (country code + area code + phone number)
6 Answers
Although the standard is talking about 15 digits maximum, a call number extension using Direct Inward Dial (DID) and Private Branch Exchange (PBX) technologies is oftenly used in order to call a specific person or department inside an organisation, which can make a phone number longer than 15 digits (note "-1234" suffix at the end):
0049 (30) 123456789-1234
In our systems we use the limit of 20 digits.
Actually, the question asks for an "international" phone number but mentions an area code which some nations don't have. In E.164 the national part was found be no more than 12 digits at the time of writing. Then they added a country code and atleast a "+" for the prefix.
Longer subscriber numbers may be possible however and we know that they do get assigned in some regions of the world. The technical limitation for that can be found in the 3GPP standards (like GSM) and ISDN standards (like DSS1) which have 10 bcd-encoded bytes for the subscriber number - plus a byte for the prefix which can be up to 4 digits to be dialled. That adds up to a limit of 24 digits for a viable subscriber number.
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