I was very peripherally involved in the Verizon One project when I was at Verizon. It's a PSTN phone. I'm sure you could plug it into an ATA, including the one supplied with Verizon Voicewing, but then you would be able to use it only as a regular phone and wouldn't benefit from the other features. iobi is, as you say, a PSTN service.

I suspect that Verizon One has only one line coming out bundling the voice and data portions bundled. I feel this way because the DSL modem is builtin. If that is the case, then you can not plug VO into an ATA, which in turn needs to be plugged into VO. Also one neds a splitter to split the voice and data portion of the DSL line.

Maybe I was trying to draw too fine a distinction. Plugging Verizon One into an ATA would give you a working cordless telephone, but the DSL router/modem/iobi would all, I think, fail. That would be a rather expensive cordless deskset.

I don't know if there is one line or two (which is to say - is the splitter in the phone or does one use a traditional splitter?). If the former, then I think you could probably use all the features except the iobi.