As with any evaluation of hardware vendors, an analysis of VoIP manufacturers will show they run the gamut in terms of price, maturity, features, etc. But one thing that seems unusual is that in the VoIP space the products with the most innovative features don't necessarily demand the highest prices.
My armchair analysis of VoIP products indicates that you can expect to pay the most for systems with robust management features and, of course, for big name brands (which, arguably, is worth a lot, especially if you require service after the sale and investment protection). But don't overlook the small fish. They are putting out systems with some really interesting features you should look into, especially if you're running a smaller organization with fewer concerns about integration and management hassles.
For an example of an innovative feature check out what Mitel and 3com are doing. They are working on IP phones that sport infrared ports that can communicate with PalmOS devices. This allows users to initiate IP calls on the phone from their contacts list on their Palm handheld. It also allows users to move their IP Phone settings easily from one IP Phone to another.
Another excellent feature comes in the form of phones that support VoIP and also have an analog port. These sort of two-line phone can solve a lot of problems for a small business or a mid-sized one with SOHO users. For starters, it lowers risk by enabling fall-back to a reliable technology. Second, it eliminates the need for complex and expensive 911 solutions. Also, it can be very cost effective, as it doesn't require expensive VoIP gateway hardware.
Of course, this is the tip of the iceberg compared to the development with WiFi and security and many other features. But the point is to not lose sight of why we're excited about VoIP: we can increase productivity in novel ways and save money at the same time. It sure seems like some vendors' offerings accomplish neither, so keep an eye on what's out there.
Tom Lancaster, CCIE# 8829 CNX# 1105, is a consultant with 15 years experience in the networking industry, and co-author of several books on networking, most recently, CCSPTM: Secure PIX and Secure VPN Study Guide published by Sybex.