If wideband voice is to become a reality, carriers must invest in upgrades to their VoIP networks, and that could take five to 10 years, Knight says, although Rodman is more optimistic, estimating three to five years. To establish HD VoIP calls using SIP, networks must have the intelligence to negotiate the use of HD codecs.

Despite its advantages, HD voice is not for everybody. Companies that have recently invested in systems may want to wait until their next upgrade cycle, Bumbernick says. And if they are just moving to VoIP but have doubts about whether their IP networks will support it, they should invest in network upgrades first and foremost, he says.

But for companies that already have VoIP and are looking to refresh their gear, HD may be a wise investment, he says. If the new voice system is slated for an eight- to 10-year life, it makes sense to have it HD-capable. "You're best served to choose technology that will get you as far down that eight-to10-year path as possible," he says.

Once the IP PBX supports HD, companies can upgrade their handsets incrementally to support wideband, he says. Key executives, for example, that would benefit from clearer calls could get the more expensive HD phones now, while others keep narrowband handsets.

Adhering to HD codec standards is essential if businesses hope to share the improved experience with partners they talk to. There are several, such as G.722, G.722.1 and G.722.2 all of which produce wideband voice but require different amounts of network bandwidth to send their encoded signals -- 64Kbps, 24Kbps and 10Kbps, respectively.