| iec.ch | International Electrotechnical Commission |
| europa.eu.int | Europa - The European Union On-line |
| etno.be | European Telecommunications Network Operators' Association |
| gc.ca | Canadian Radio-television and Telecommunications Commission (CRTC) |
| doc.gov | National Telecommunications and Information Administration |
| itu.int | International Telecommunication Union (ITU) |
| iso.ch | ISO. International Organization for Standardization |
| ieee.org | Institute of Electrical and Electronics Engineers |
| fcc.gov | USA - Federal Communications Commission (FCC) |
| etsi.org | European Telecommunications Standards Institute (ETSI) |
| etsi.org | www.etsi.org/ |
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