ITU

Committed to connecting the world

ITU-T Recommendations

The main products of ITU-T are Recommendations (ITU-T Recs) - standards defining how telecommunication networks operate and interwork. See below list for access. ITU-T Recs have non-mandatory status until they are adopted in national laws. Levels of compliance are however high due to international applicability and the high quality guaranteed by the ITU-T's secretariat and members from the world's foremost ICT companies and global administrations.

There are over 4000 Recommendations in force on topics from service definition to network architecture and security, from broadband DSL to Gbit/s optical transmission systems to next-generation networks (NGN) and IP-related issues, all together fundamental components of today's information and communication technologies (ICTs).

Membership of ITU-T gives exclusive rights to access working documents of standards under development - tomorrow's ICTs. The vast majority of all Recommendations are available in electronic (PDF) form free of charge to all once a final editing process is complete. Texts that are not free of charge include common ITU-T | ISO / IEC texts for which special arrangements exist. Find out more about membership here.

ITU-T Recommendations are available through a Website in tree views, offering multi-criteria search and cross navigation facilities. Each ITU-T Recommendation is cross-linked to corresponding work programme,approval process, formal descriptions (more than 1400 freely available), test signals (more than 15 GB of data freely available), supplements, implementer's guide and IPR statements when applicable.

A to M Series

A : Organization of the work of ITU-T

D : General tariff principles

E : Overall network operation, telephone service, service operation and human factors

F : Non-telephone telecommunication services

G : Transmission systems and media, digital systems and networks

H : Audiovisual and multimedia systems

I : Integrated services digital network

J : Cable networks and transmission of television, sound programme and other multimedia signals

K : Protection against interference

L : Construction, installation and protection of cables and other elements of outside plant

M : Telecommunication management, including TMN and network maintenance

N to Z Series

N : Maintenance: international sound programme and television transmission circuits

O : Specifications of measuring equipment

P : Terminals and subjective and objective assessment methods

Q : Switching and signalling

R : Telegraph transmission

S : Telegraph services terminal equipment

T : Terminals for telematic services

U : Telegraph switching

V : Data communication over the telephone network

X : Data networks, open system communications and security

Y : Global information infrastructure, Internet protocol aspects and next-generation networks

Z : Languages and general software aspects for telecommunication systems