The promise of IP telephony has been a siren song for years . . . with exceptionally loud hosannas emanating from a certain network equipment vendor in San Jose. But now the chorus has been joined by even more voices. One is Microsoft, which is releasing the voice-over-IP enabled version of Windows CE next month, and also has a massive internal effort underway around VoIP.The promise of IP telephony has been a siren song for years . . . with exceptionally loud hosannas emanating from a certain network equipment vendor in San Jose.But now the chorus has been joined by even more voices. One is\u00a0Microsoft, which is releasing the voice-over-IP enabled version of Windows CE next month, and also has a massive internal effort underway around VoIP.Even more interestingly, IP telephony appears to be picking up steam in the enterprise. Nemertes Research recently heard from roughly 50 IT executives, and their message was clear: IP telephony is here. More than 80% are using the technology: 64% in a production environment and 20% in trials. And hats off to the folks in Redmond for focusing on the right issues: Front and center concerns are integration with enterprise applications and mobility.Now let's talk about some folks that aren't quite in tune with the real issues: service providers. Here are a few things AT&T, Equant, Infonet, MCI, Sprint and others leaping into the IP telephony fray can do more wisely:Come up with a better ROI story. Service providers are still hung up on the notion that the true value proposition of IP telephony lies in bypassing the toll. That doesn't work so well when the so-called "tolls" are, well, the services you sell."When we researched the math, we couldn't make AT&T's (IP telephony) offering work. It's because they're competing with themselves - and why would they want to drive down revenue?" says the communications director for a large manufacturing firm.Emphasize managed services - and deliver. "I would prefer to buy (enterprise IP telephony) as a service from carriers," the global telecom manager for another large manufacturer says. To get this business, telcos should integrate with leading equipment vendors, which paves the way for provider-managed IP telephony services. AT&T already has lined up agreements with Cisco and Avaya, and MCI says it's doing the same.Second, they should help IT executives with deployments. Over a third of IT execs said poor voice quality was holding them back from further IP telephony deployments - yet poor quality is almost always an implementation issue, often caused by inexperienced, value-added resellers or integrators. IT executives need qualified help of the kind that carriers could provide.Deliver integrated mobile solutions. The most important IP telephony cost-justifier cited by IT executives was the ability to enhance mobility. This includes not only wireless integration, but also the ability to change locations seamlessly while remaining on the corporate voice (and particularly voice mail) network. People get around this today by using their cell phones as their primary phones, but such an approach drives up a corporation's cellular costs and limits available functionality. Many companies would leap at the chance to reduce cellular costs and improve mobile connectivity at the same time.