The whole trail is kind of convoluted but it seems there is a company, Klausner Technologies, with a patent for the same concept as SimulSays, SimulScribes visual voicemail solution for RIM and WinMo as well as Apple’s Visual Voicemail.
It seems SimulScribe has settled and licensed the Klausner’s patents (here and here) while Apple, Vonage, AT&T, and AOL are still in litigation. I love the smell of patent trolling in the morning.