Avaya, a major provider of PBX systems (which recently acquired Nortel’s PBX business), has formed a strategic partnership with VoIP provider Skype to collaborate on unified communications (UC). FierceVoip.com reports that the first phase of the agreement will allow Avaya customers to access Skype Connect calling features via their IP-based enterprise communication systems over SIP. Skype Connect will be accessible to companies using the Avaya Aura UC system, giving the advantage of low-cost international calls, whilst Skype’s worldwide user base will be able to call Avaya’s business customers for free or at reduced rates. Under a second phase of the deal scheduled for late 2011, Avaya and Skype plan to jointly launch new integrated UC offerings, including presence communications, instant messaging, voice and video. The move is part of a drive by Skype to expand its presence in the business communications market, where it has penetrated the small-to-medium company segment to some extent, but has thus far made less of an impact amongst large corporate users. Private equity firm Silver Lake controls Avaya and is also the majority shareholder in Skype.