Probably the largest class of UM detracters are those who, for one reason or another, don't live in Windows for their desktop OS. We've got a few Macintosh users & more than a few Unix (Linux/Solaris mostly) users. They don't get the benefits of VMO. Also, some don't have speakers on their PCs, find headsets a bother, can't play thru their phone (no VMO) or don't want their VM played to their neighbors. They don't otherwise use sound on their PCs. For them, voice messages in their e-mail mailboxes are not helpful. When they touch the VM message in whatever they are using for their email client, it gets marked as read & the TUI presents it as a saved message, rather than new. Also the MWI goes off then. And some are just chronic complainers.
We have not provided TTS yet, and probably won't. Most of our users are more email centric and not particularly mobile (there are, of course, exceptions). Nor have we integrated fax, though that is a possibility.
But most users have been very accepting. Travellers and telecommuters really like it. Training sessions get light attendance. When we've provided individual training, most who dislike it remain unconvinced.
