BT Wholesale has appointed a new chief executive as Sally Davis steps down for personal reasons.
Davis, who has been in the role since July 2007, will stay at BT until the end of October to facilitate the handover of responsibilities.
BT Wholesale provides voice, broadband and data communications services to fixed and mobile network operators, internet service providers (ISPs) and telecoms resellers in the UK.
It also supplies managed network services.
The division reported revenues of £4.21 billion last year.