My mantra has usually been that hosted telephony addresses a 10-20% slice of the corporate marketplace. And that mobile hosted solutions are only good for 10-20% of the 10-20%.
Yes, there will always be some 11-person media company in Helsinki that's used as a case study to highlight the idea, but they are always "corner cases" rather than a typical customer.
But I'm feeling particularly vindicated by the announcement today of a product that finally boots this concept into the long grass as a massmarket trend:
The branded "Vodafone PABX", launched in Portugal, along with a couple of other fixed-line offerings. Yes, I know that Voda has its own centrex-type platforms, but for me this shows that the company knows that dogmatic pursuit of fixed-mobile substitution flies in the face of commercial reality.
For whatever reason, most companies want their own box, in their office, with reassuring flashing lights on it.