What is the maximum length of any numeric geographic area address in ITU recommendation
E.164? 

Answer options:

A. 15
B. 18
C. 21
D. 22
E. 25

A

 
E.164 defines a general format for international telephone numbers. Plan-conforming numbers are limited to a maximum of 15 digits. The presentation of numbers is usually prefixed with the character + (plus sign), indicating that the number includes the international country calling code (country code), and must typically be prefixed when dialing with the appropriate international call prefix, which is a trunk code to reach an international circuit from within the country of call origination.