Fellow VoIP blogger Ted Wallingford writes that a big obstacle to consumer-branded VoIP access services entry into the enterprise space is the fact that most don't control the data connection as well as the service.
"Because most home broadband connections don't support Quality of Service (QoS) technology (which prioritizes voice traffic over non-voice traffic in order to optimize your calling experience), Vonage, Broadvoice, Lingo, and other residential VoIP providers can't guarantee you won't have drop-outs or disconnected calls," Ted writes in his excellent O'Reilly Network article, Eight Tips for Migrating to Enterprise VoIP.
"This is, coincidentally, the reason most businesses who use VoIP telephone service don't use Vonage, Broadvoice, or Lingo," Ted adds. "Instead, they use VoIP providers who can provide guaranteed Quality of Service, like the local phone company or another local or national service provider who controls not only the VoIP service, but also the data connection that pipes it to you--usually an internet T1."
Ted correctly notes that XO Communications, SBC, and some other large phone companies have started to offer this type of data-connection service. "It's far superior to Vonage's broadband VoIP," he writes.
By the way, check out Ted's new book, Switching To VoIP. It's aimed at the prospective enterprise VoIP user, and contains more tips than just about any consultant or systems integrator could come up with.