Wichita, Kansas-based Brite Voice Systems Inc has won a $7m contract to support a marketing campaign by Cellnet Mobile Communications Ltd to relaunch Call-back, its intelligent messaging service. Cellnet, jointly owned by British Telecommunications Plc and Securicor Group Plc, has bought four further Voice Services Directors for Callback. It is the largest single order ever for Brite making a total committment from Cellnet of about $18.6m in the past two years, Brite said.