The name change will be effective immediately, although shares will not be traded as O2 until the de-merger is completed, this is expected by November. BT Wireless divisions will begin using the brand from next spring. The company to be rebranding is just one of many from the BT stable.
BT announce the birth of O2
According to the Financial Times the wireless division of BT has been renamed O2 ahead of its spin-off later this year.