PM² Telecommunication GmbH
- Siemensstraße 12b, 63263 Neu-Isenburg
- +49 (6102) 81290-0
- +49 (6102) 81290-19
telecommunication software gmbh
- Grabenweg 64, 6020 Innsbruck
- +43 (512) 9390-0
- +43 (512) 9390-333
International Telecommunication Union (ITU)
- Place des Nations, 1211 Geneva
- +41 (22) 730-5111
- +41 (22) 733-7256
Krueger Consulting
- Kaiserstr.52, 80801 München
- +49 (89) 349460
- +49 (89) 396111
WeyTeCon Weyerstraß Telecommunication
- Siehdichum 4, 17217 Penzlin
- +49 (3962) 212753
- +49 (3962) 212754
elcTec electronic computer telecommunication
- +49 (8142) 444840
- +49 (8142) 444836
OneTel Telecommunication GmbH
- Frauenbergstraße 31-33, 35039 Marburg
- +49 (1805) 108600
- +49 (1805) 108601
Tele2 Telecommunication GmbH
- Donau-City-Strasse 11, 1220 Wien
- +43 (800) 240020
- +43 (800) 240022
cit GmbH - computer integrated telecommunication
- Kirchheimer Str. 205, 73265 Dettingen/Teck
- +49 (7021) 950858-0
- +49 (7021) 950858-9
GPN - Global Private Network Telecommunication GmbH
- Haydngasse 17, 1060 Wien
- +43 (1) 311711-32