At Voicecon, John at Aastra showed me the nifty new Asterisk based PBX that was just introduced. Aastra also offers Microsoft's Response Point PBX, the key system replacement for 5 to 50 employees. The MS RP system is about $2750 -- about the same cost as PBX systems from other vendors in the Small Biz space. If Aastra offered me a choice of Asterisk or Microsoft, it would be a no-brainer to go Asterisk.
My Response to MS RP is that my experience with MS O/S offerings has been no fun. After the latest XP Updates, my audio driver and USB ports stopped working. (My USB ports are STILL not working -- hints anyone?). My Sprint PPC-6700 is an MS based smartphone that locked up on me while surfing Yahoo Sports via IE. Remember Win98, SE, ME???
To me, placing my phone system in the hands of bloated coders who are newbies to voice is scary. I can barely get by with limited email, but if I don't have dial-tone, I could lose business. (Heck, MS IPTV makes me think that at some point I will miss the end of the game because of an update or reboot.)
I wasn't the only one feeling this way either. Read the review at Entrepreneur mag.
I will say now that MS and Cisco are fighting it out in Tele-Presence and VoIP, the noise level will spill over into mainstream. That means more opportunities to sell Hosted PBX, IP Phones, Unified Messaging, and Telco 2.0