Avaya, the manufacturer of corporate phone systems and software, has paid $915 million to acquire Nortel Networks' enterprise business, its second-largest unit by revenue. The deal, which is subject to Canadian and US court and regulatory approvals, includes $15 million for an employee retention program. Basking Ridge, New Jersey-based Avaya had previously made a $475m stalking horse offer for the enterprise unit, which makes phone equipment and networks for businesses and has annual revenues of around $2.4 billion.