ITU roles and numbering plans

Roles of ITU

The International Telecommunication Union (ITU) is the UN specialised agency for ICT, founded in 1865 and based in Geneva. Its roles are:

1. Radio spectrum and orbit management (ITU-R): allocates frequency bands and satellite orbit slots worldwide and maintains the Radio Regulations to avoid interference.
2. Standardization (ITU-T): develops Recommendations such as E.164 (numbering), G.711 (PCM), Q.700 (SS7), H.323, so that networks and equipment work together worldwide.
3. Development (ITU-D): helps developing countries with infrastructure, policy, regulation and training; works to bridge the digital divide.
4. International numbering and tariffs: assigns country codes and sets accounting principles for international calls.
5. Cooperation and safety: promotes international cooperation, emergency telecommunication, cybersecurity and accessibility.

Numbering plan

A numbering plan gives a unique number to each subscriber and fixes the digits used for routing and charging.

National numbering plan

 [Trunk prefix][Area code][Exchange code][Line no.]
       0           1           44          12345

• Trunk prefix (0 in Nepal) for long distance calls.
• Area / national destination code (NDC): e.g. 1 Kathmandu, 61 Pokhara, 21 Biratnagar; mobile codes 984, 980.
• Subscriber number: exchange code + line number.
• Open plan: short local numbers, prefix + area code for other areas (Nepal, India, UK).
• Closed plan: fixed-length number always dialled (USA, 10 digits).

International numbering plan (ITU-T E.164)

 [Intl prefix][CC][National significant number]
      00       977        1 4412345

• International prefix: 00 (011 in North America), shown as "+".
• Country code: 1–3 digits; first digit is the world zone (1 North America, 2 Africa, 3/4 Europe, 5 Latin America, 6 Oceania, 7 Russia, 8 East Asia, 9 Asia/Middle East).
• NSN: national number without the trunk prefix.
• Maximum international number length: 15 digits.