Alcatel, the French telecommunications equipment group, on Friday moved to plug its gap in an emerging mobile technology by purchasing a Texas-based technology start-up for $250m, its biggest acquisition in four years.

The deal to buy Spatial Wireless was accompanied by the disposal of Alcatel's electrical power system business, with annual sales of €220m ($268m), to US private equity group Ripplewood. Alcatel also announced the acquisition of a conference technology company for $27m.