Most people - about 75-80% of the population are slow adapters at best, afraid to change at worst. Most people don't like change. When Alice in purchasing gets an Aastra phone to replace her Rolm phone, she will be paralyzed in her job. After 15 years of hitting the same 4 buttons - buttons now missing from her new fangled VoIP phone - she will be afraid of the phone. Also, her fear of the phone will frustrate not only other employees, but customers as well. (Not to mention the VoIP provider's tech support department that will have to explain call transfer and call pick-up methods daily).
THIS then is the hurdle of not just VoIP providers and phone manufacturers, but also wireless providers and manufacturers. Selling the Invisible is difficult, especially when so much FUD surrounds it. How do you counter that? Education for one. Sneezers for another. (See