There's a there there

ENUM and SIP.  Two acronyms that mean nothing unless you’re a
Net-savvy telecom geek (like yours truly).  Word to the wise: pay
attention.  These are the bridges between the the world of
telephony and the world of the Internet.  People like Jeff Pulver and James Seng are recognizing that something significant is afoot in the arcane world of network addressing and signaling. 

Voice over IP has been around commercially for at least eight years,
but it’s now reaching a critical stage of maturity.  One side is
consumer adoption of services like Vonage and Skype, but that’s just
surface activity.  Deep integration on the back end is a more
profound shift.  It’s the difference between making a phone call
over the Internet, and voice as an internetworking application. 
Or to put it another way, the different between the Internet as a
subset of telecommunications, and telecommunications as a subset of the
Internet.