Esat BT, is part of the BT Group, based in Ireland originally called Esat Telecom; the companies main business is in fixed line business in Ireland - services such as internet access, prepaid accounts and cards for voice. Esat Digifone is also traditionally part of the group Esat Telecom, though it was later spun off, the company is also associated with Denis O'Brien its original chairman and chief executive. The companies main network is built along the Iarnród Éireann rail network, completed in 1999, and while it does not currently install telephone lines its main competitor is Eircom. Esat BT owns the ISP Ireland On-Line.