Setting up the phone system for a help desk in the average corporate environment is problematic, because you must live within the limitations of the organization's existing phone switch. Few of these support such useful features as e-mail-delivered voice mail, n-way conference calling, and hunt-me-down call blasting. Using the enterprise phone system for your call center may also make it difficult for telecommuters and other outside users to call into the system.

VoIP providers like AT&T, Lingo, and Vonage, however, offer all of these features and have the advantage of giving offsite users ready access. In fact, I argue that severing the help desk from the in-house phone system is a valuable reliability enhancement. I tested the three listed commercial VoIP offerings, along with the open-source Skype, and found compelling reasons to choose AT&T over the others. More about that in a moment, but first take a look at how a VoIP package can give you a help desk-in-a-box for about $50/month.

The three big features of VoIP that help desk managers will love are Web-based message management, inbound call redirecting, and n-way conference calling. Web-based message management gives you browser access to incoming calls and voicemail messages stored as audio files. You can easily forward those messages to anyone via e-mail, or store them as attachments in a trouble ticket archive. You can also automatically forward incoming voice messages for re-broadcast to your entire support staff. This gives you a permanent, pervasive record of what help desk callers said when they called in.

Inbound call redirecting lets you instantly change where callers land. You can forward all calls to an on-duty staffer's cellphone, or send them all straight to voicemail while the help desk staff is in a meeting. You also can forward incoming calls to more than one destination simultaneously, a feature called call blasting, which helps your callers get through to an available staffer quickly.

N-way conference calling lets you bridge four or more people into a call during the problem-solving process. Most corporate phone systems support three-way conference calling, but that's rarely enough to untangle problems that might involve several consulting parties. If the VoIP conferencing feature is also Web-enabled, VoIP solves the problem of dropping only the party you want to drop, by letting you simply click on that party in the Web-displayed list of people on the call.

There are lots of other features in VoIP systems that add additional value to the help desk application, but these are the big three. Of the four systems I tested -- AT&T, Lingo, Skype, and Vonage -- I found AT&T's CallVantage the best for the help desk. Lingo and Vonage both lacked features found in CallVantage, and voice quality was sometimes lacking as well. AT&T had consistently great sound. Skype, the open-source solution, is very interesting, but lacks the off-the-shelf packaging of commercial VoIP. Even though it can cost much less per month, since you only pay for calls that leave the Skype network to or from a landline, the hidden cost of staff labor overwhelms this advantage.

CallVantage's best features include a 10-way Web-enabled conference calling bridge that lets you initiate calls from your browser and easily drop just the callers you want during the course of a conference; LocateMe, a call blaster that can either sequentially or simultaneously call five destination numbers to get a help desk staffer on the phone; fax e-mail forwarding; caller-ID name and number in pager notifications, and call filtering, which lets you direct calls to voicemail based on the caller-ID information. AT&T's $50 small-business package includes two VoIP phone lines and all the necessary hardware. I found that with only minor e-mail-server scripting I was able to tie voicemail attachments into my existing trouble ticket system.

The best feature of all of these systems is that they're inexpensive to try out. All offer a trial plan that you can buy without making a long contract commitment.