Maximum Length for International Phone Numbers

The following table shows how to calculate the safe maximum length for international phone numbers.

Is there a phone format for the country?	Then, the safe maximum length for international phone number is
Yes	C + 2N + E + 2 ≤ 40
No	2C + 2N + E + 2 ≤ 40

In the formulae in this table:

• C is the length of the country code.

• N is the length of the city code and the subscriber number, including any formatting, such as spaces or hyphens.

• E is the length of the extension number.

The following table shows an example calculation of the maximum length of an international phone number ([phone] x 123).

International phone number	Maximum length for each element (C, N, E)
+834	C=3
91 518–400	N=10
x 123	E=3