Mitel Corp. cleared an important hurdle.

The British government approved British Telecommunications PLC’s bid to buy controlling interest in the Canadian telephone switching equipment maker. The deal gives British Telecom a North American toehold from which it hopes to expand aggressively into the United States. The British Department of Trade and Industry approved the purchase of a 51% interest in Mitel by British Telecom for $230 million. Mitel, which is based in Kanata, Canada, has lost money in recent years.