In all fairness, these drawbacks in Enterprise Lync have caused many more untrue rumors to circulate about the product, too.

Microsoft has dismissed some of them: Lync does support site-to-site failover. In a well-planned system, if one server role goes down, the others need not be affected. And Direct SIP, Microsoft's interconnection with PBX systems, supports multiple vendors' products, Microsoft says. These include and Avaya.

Julie Bort is the editor of Network World's Microsoft Subnet and Open Source Subnet communities. She writes the Microsoft Update and Source Seeker blogs. Follow Bort on Twitter @Julie188.

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