I'm not sure if all of our clients can tell but we've been leveraging VOIP for going on two years now. We've traditionally used Vonage for each individual phone line and Accessline for our auto-attendant. A couple of things we've learned through the process: Auto-Attendants don't project that you're super professional...they say you don't care about the customer. - We found out the hard way through people getting lost in our phone system that auto-attendants are not as user friendly and speedy as we would like. We actually share a receptionist (Lucie) with our partner, Communicators Group. We had a Vonage line installed at their office in Brattleboro that receives all of our incoming calls. She can transfer the calls to any phone in North America at no additional cost. Touchtone doesn't always work on teleconference lines - For some reason, when we try to use the free (maybe that's the issue) teleconference number that comes with Adobe Acrobat Connect, it won't recognize the access code we enter more than half the time when we use a vonage line. We're a little nervous about Vonage - Given the recent patent stirrings of vonage, we've have some concerns about where they're heading. Our main line is "hosted" by Accessline so we can pretty much change at will for our desk lines but it still gives us pause. We're actually considering Skype as a replacement. The chat tool in and of itself is pretty helpful (particularly for group chat) and the video conferencing works nicely. Vonage SoftPhone is AWFUL - Particularly on the Mac, where it crashes pretty much every time we use it, the softphone is terrible. We basically abandoned any concept of using it. The only thing we've been successful with really is the devices that let you connect a standard phone in. The wireless phone was pretty awful as well. (Do you think we try a lot of different stuff)? Virtual numbers save customers long distance - One of the key benefits of having VOIP has been the ability to get virtual numbers for our remote people. Danielle, our developer in Miami, has a Keene based phone number that makes it feel like she is closer than ever. I think our biggest challenge is that hodge podge nature of the phone system. The vonage system is really not set up for multiple lines. We would continue forever if they had a well integrated business system. All this being said, it's been pretty good and a heck of a lot more economical than 12 phone lines through Verizon. I'll report back on the Skype testing we're doing now but they seem to have much higher quality in the call. Particularly cool is the Polycom Communicator which plugs in via USB.