ITU-T E.164 International Phone Number Format: Country Codes & Trunk Prefixes

1. Anatomy of an ITU-T E.164 Number

Under ITU-T Recommendation E.164, every international public telecommunication number consists of up to 15 digits (excluding the + prefix) divided into three components:

  +   44        7700        900077
 [+] [CC]      [NDC]         [SN]
      |          |             |
      |          |             +-- Subscriber Number (6-8 digits)
      |          +---------------- National Destination Code / Mobile Prefix
      +--------------------------- Country Calling Code (1-3 digits)

2. The #1 Formatting Mistake: Leaving the Domestic Trunk Prefix (0)

In most European and Asian countries, domestic mobile numbers begin with a trunk prefix 0 when dialed locally, which must be dropped when converting to international E.164 format:

3. How NEXUSOTP Formats Numbers for You

When you rent a number in our Telegram Bot (@nexusotps_bot), we display both the full E.164 string (e.g., +447700900077) and the national subscriber digits (7700900077). If a website’s country dropdown already displays +44, paste only the subscriber digits so you do not accidentally submit +44447700900077. You can test any number format instantly using our E.164 Phone Number Validator.