VoIP stability and interoperability is pretty good, but don't expect features to be shareable anytime in the near future.
VoIP has been coming for years, with the first products showing up in the mid-1990s. But it hasn't been until recently that the standards have solidified. Until recently, concerns about the reliability of IP-based voice networks have kept many companies from jumping into VoIP. But most of VoIP's stability problems have been resolved, say both analysts and users.
In fact, because they let users plug their phones directly into an Ethernet network, VoIP networks can turn out to be even more resilient than standard voice networks, no matter whether users are on the local network or working remotely. "IP-based communications lets a mobile worker have all the functionality of the corporate office," says Pulver.com's Jeff Pulver.
Carriers insist they can offer the same reliability for VoIP services, too. "The reliability of [carrier] IP networks is now as good as the standard voice network," maintains Hossein Eslambolchi, president of AT&T Labs.
As to interoperability, connections between VoIP switches also get good grades, allowing systems from different vendors to set up and transmit calls easily. But you won't usually find the exact same features on two different vendors' switches, and you can't ordinarily use one vendor's smart phones on another vendor's switch. That's why most users prefer to roll out single-vendor installations until those problems are resolved.
However, a solution is on the horizon: SIP, or Session Initiated Protocol, an industry scheme designed to homogenize a wide range of VoIP call processes. SIP allows smart phones to set up calls using standardized requests. "As SIP gets more penetration," says Eslambolchi, "customers will start seeing a huge amount of value" from VoIP. In the meantime, IT departments would do well to question vendors' support of standards such as SIP, and to ensure that they're getting the level of interoperability they need.
Ask VoIP equipment vendors:
With whose equipment have you tested your equipment, so I can be sure my gear will work in harmony with theirs?
How complete is your support of SIP today, and what's your roadmap for tomorrow?
Ask communications carriers:
How can you convince me that your IP voice services are 100 percent reliable?