I couldn't agree more and that is why I invested in Michael Robertson's Sipphone over 18 months ago. You can see my blog post here about it: http://www.beyondvc.com/2006/02/why_we_invested.html. Anyway, it reminds me of the days when AOL could only email AOL users and Compuserve only other Compuserve users. I am already seeing a move towards open standards as companies like Nokia are integrating a SIP stack in their dual mode wifi phones and Cisco and Microsoft and Avaya are using this as the basis for their VOIP platforms