2015–2019One.Vip was created by the 2015 merger of One, owned by Telekom Slovenije (which had acquired it from OTE of Greece), and Vip operator, owned by A1 Telekom Austria Group, which now owns the entirety of the company (up from 55%, after Telekom Slovenije agreed to give up its 45% stake).
2019–presentOn 5 September 2019, the One.Vip brand was phased out in favour of the A1 brand, as had been done in all other European markets except Serbia (where the Vip mobile brand will be replaced by A1 in 2020). This came a month after Velcom in Belarus also rebranded to A1.
| Part of América Móvil (59.7%)
| Main companies:|
Telekom Deutschland | Hrvatski Telekom (Crnogorski Telekom (76.53%) | HT Mostar (39.1%)) | Magyar Telekom | Makedonski Telekom | OTE (40%) | Slovak Telekom | Telekom Romania (54%) (via OTE) | BT (12%) | Magenta Telekom