UK incumbent BT said Wednesday that Paul Reynolds, one of the key figures behind the carrier’s 21st Century Network strategy, has resigned.

Reynolds will be leaving BT in September to take up the position of CEO of Telecom New Zealand.

Reynolds joined BT in 1983, straight out of University, and joined the board in November 2001 as chief executive of BT Wholesale.

In the latter part of his 24 year stint at the carrier, Reynolds played a key part in the design and creation of Openreach and has led 21CN from the outset.

BT has not yet revealed who will take Reynolds’ place.