International Telecommunications Union - You can download relevant standards from this site.
Knowledge Transfer Network
National Institute of Standards and Technology - Workshop on Synchronisation in Telecommunication Systems.
The National Physical Laboratory run the Time and Frequency User Group in the UK.
Nigel Allen's online library of useful telecoms information/contacts etc.
Ofcom is the regulator for the UK communications industries, with responsibilities across television, radio, telecommunications and wireless communications services.
The Russian Federation Information Centre - GLONASS information.
WORLDTIME® is a service featuring an interactive world atlas, information on local time, as well as sunrise and sunset times in several hundred cities, and a database of public holidays worldwide.
United Kingdom Accreditation Service - Home Page
US Coastguard Navigation Centre
Time Service Department of the US Naval Observatory. Good info on GPS plus time of day.