| 1 | Arbeitgeberverband comunity, Arbeitgeberverband für Telekommunikation und IT e.V. | Germany | Bonn |
| 2 | Comfortcharge GmbH | Germany | Bonn |
| 3 | congstar GmbH | Germany | Cologne |
| 4 | Cosmote E-Value Contact Center Services Societe Anonyme | Greece | Xanthi |
| 5 | COSMOTE PAYMENTS ELECTRONIC MONEY SERVICES SINGLE MEMBER SA | Greece | Marousi |
| 6 | Cosmote Technical Services Single Member S.A | Greece | Athens |
| 7 | Cosmote TV Productions & Services A.E. | Greece | Kifissia |
| 8 | DeTeAssekuranz - Deutsche Telekom Assekuranz-Vermittlungsgesellschaft mbH | Germany | Cologne |
| 9 | Detecon International GmbH | Germany | Cologne |
| 10 | DeTeFleetServices GmbH | Germany | Bonn |
| 11 | Deutsche Telekom (UK) Limited | United Kingdom | Welwyn Garden City |
| 12 | Deutsche Telekom AG | Germany | Bonn |
| 13 | Deutsche Telekom Clinical Solutions GmbH | Germany | Bonn |
| 14 | Deutsche Telekom Cloud Services d.o.o | Croatia | Zagreb |
| 15 | Deutsche Telekom Cloud Services EPE | Greece | Kifissia |
| 16 | Deutsche Telekom Cloud Services Kft. | Hungary | Budapest |
| 17 | Deutsche Telekom Cloud Services S.R.L. | Romania | Bucharest |
| 18 | Deutsche Telekom Cloud Services s.r.o. | Slovakia | Bratislava |
| 19 | Deutsche Telekom Cyber Security Austria GmbH | Austria | Vienna |
| 20 | Deutsche Telekom Geschäftskunden GmbH | Germany | Bonn |
| 21 | Deutsche Telekom Global Business & Security Schweiz AG | Switzerland | Münchenbuchsee |
| 22 | Deutsche Telekom Global Business Solutions Belgium NV | Belgium | Machelen |
| 23 | Deutsche Telekom Global Business Solutions Brasil Ltda | Brazil | Sao Bernardo do Campo |
| 24 | Deutsche Telekom Global Business Solutions China (HK) Limited | China | Hong Kong |
| 25 | Deutsche Telekom Global Business Solutions France SAS | France | Puteaux |
| 26 | Deutsche Telekom Global Business Solutions GmbH | Austria | Vienna |
| 27 | Deutsche Telekom Global Business Solutions Iberia S.L. | Spain | Madrid |
| 28 | Deutsche Telekom Global Business Solutions Italia S.r.l. | Italy | Rozzano |
| 29 | Deutsche Telekom Global Business Solutions Nederland B.V. | Netherlands | Utrecht |
| 30 | Deutsche Telekom Global Business Solutions Singapore Pte. Ltd. | Singapore | Singapore |
| 31 | Deutsche Telekom Global Business Solutions UK Ltd. | United Kingdom | Milton Keynes |
| 32 | Deutsche Telekom Healthcare and Security Solutions GmbH | Germany | Bonn |
| 33 | Deutsche Telekom Individual Solutions & Products GmbH | Germany | Bonn |
| 34 | Deutsche Telekom IoT GmbH | Germany | Bonn |
| 35 | Deutsche Telekom IT GmbH | Germany | Bonn |
| 36 | Deutsche Telekom ITTC Hungary Kft. | Hungary | Budapest |
| 37 | Deutsche Telekom MMS GmbH | Germany | Dresden |
| 38 | Deutsche Telekom Nordic A/S | Denmark | Copenhagen |
| 39 | Deutsche Telekom North America Inc. | United States | Wilmington |
| 40 | Deutsche Telekom Privatkunden-Vertrieb GmbH | Germany | Bonn |
| 41 | Deutsche Telekom Security GmbH | Germany | Bonn |
| 42 | Deutsche Telekom Service GmbH | Germany | Bonn |
| 43 | Deutsche Telekom Services Europe Czech Republic s.r.o. | Czech Republic | Brno |
| 44 | Deutsche Telekom Services Europe Romania S.R.L. | Romania | Bucharest |
| 45 | Deutsche Telekom Services Europe SE | Germany | Bonn |
| 46 | Deutsche Telekom Services Europe Slovakia s.r.o. | Slovakia | Bratislava |
| 47 | Deutsche Telekom Systems Solutions Slovakia s.r.o. | Slovakia | Kosice |
| 48 | Deutsche Telekom Technik GmbH | Germany | Bonn |
| 49 | Deutsche Telekom Tiefbau GmbH | Germany | Bonn |
| 50 | Deutsche Telekom TSI Hungary Kft. | Hungary | Budapest |
| 51 | DTAG Global Business Solutions Mexico, S.A. de C.V. | Mexico | Puebla |
| 52 | Germanos Industrial and Commercial Company of Electronic Telecommunication materials and supply of Services Single Member | Greece | Athens |
| 53 | Hellenic Telecommunications Organization S.A. (OTE) | Greece | Marousi |
| 54 | Hrvatski Telekom d.d. | Croatia | Zagreb |
| 55 | I.T.E.N.O.S. International Telecom Network Operation Services GmbH | Germany | Bonn |
| 56 | Magyar Telekom Telecommunications Public Limited Company | Hungary | Budapest |
| 57 | Makedonski Telekom AD Skopje | Macedonia | Skopje |
| 58 | operational services GmbH & Co. KG | Germany | Frankfurt/Main |
| 59 | OTE ASFALISI INSURANCE AGENCY SOCIETE ANONYME | Greece | Marousi |
| 60 | OTE EDUCATIONAL SINGLE MEMBER SOCIETE ANONYME | Greece | Athens |
| 61 | OTE Estate S.A. | Greece | Athens |
| 62 | PASM Power and Air Condition Solution Management GmbH | Germany | Munich |
| 63 | rola Security Solutions GmbH | Germany | Cologne |
| 64 | Slovak Telekom, a.s. | Slovakia | Bratislava |
| 65 | Software Daten Service Gesellschaft m.b.H. | Austria | Vienna |
| 66 | Telekom Deutschland GmbH | Germany | Bonn |
| 67 | T-Mobile Austria GmbH | Austria | Vienna |
| 68 | T-Mobile Austria Holding GmbH | Austria | Vienna |
| 69 | T-Mobile Czech Republic a.s. | Czech Republic | Prague |
| 70 | T-Mobile International Austria GmbH | Austria | Vienna |
| 71 | T-Mobile Polska S.A. | Poland | Warsaw |
| 72 | T-Systems Austria GesmbH | Austria | Vienna |
| 73 | T-Systems Belgium Road Charging NV | Germany | Machelen |
| 74 | T-Systems Client Services GmbH | Germany | Bonn |
| 75 | T-Systems Data Migration Consulting AG | Switzerland | Kreuzlingen |
| 76 | T-Systems do Brasil Ltda. | Brazil | Sao Paulo |
| 77 | T-Systems France SAS | France | Rueil-Malmaison |
| 78 | T-Systems Information and Communication Technology India Private Limited | India | Pune |
| 79 | T-Systems Information Services GmbH | Germany | Berlin |
| 80 | T-Systems International GmbH | Germany | Frankfurt/Main |
| 81 | T-Systems ITC Iberia, S.A. | Spain | Barcelona |
| 82 | T-Systems Limited | United Kingdom | London |
| 83 | T-Systems Mexico, S.A. de C.V. | Mexico | Puebla |
| 84 | T-Systems Nederland B.V. | Netherlands | Utrecht |
| 85 | T-Systems Nordic A/S | Denmark | Copenhagen |
| 86 | T-Systems North America, Inc. | United States | Wilmington |
| 87 | T-Systems on site services GmbH | Germany | Berlin |
| 88 | T-Systems P.R. China Ltd. | China | Beijing |
| 89 | T-Systems Road User Services GmbH | Germany | Bonn |
| 90 | T-Systems Schweiz AG | Switzerland | Münchenbuchsee |
| 91 | T-Systems Singapore Pte. Ltd. | Singapore | |
