11/3/2009 -- The good news for Cisco Systems Inc. and other prominent players is that the Voice-over-IP (VoIP) segment continues to buck an otherwise downward trend in the broader communications and telephony segments.

With Cisco betting big on surging demand for unified communications and collaboration (UCC) technologies, that's an extreme positive development.

The longer-term prospects for VoIP seem equally positive, with both business and residential adoption expected to grow over the next half-decade.

"Demand for residential and business VoIP services continues to grow even as spending in other communication areas tightens," said Diane Myers, director analyst for service provider VoIP and IMS with market watcher Infonetics Research, in a statement.

Demand for residential VoIP services, in particular, continues to skyrocket, Myers said. In the first half of 2009, residential subscribership was up by 14 percent from late 2008, while the worldwide VoIP market neared $21 billion. That's a big chunk of change, according to Myers.

Business-related VoIP adoption seems to have slowed, but Myers and Infonetics expect that this will change, too. "[W]hile managed IP PBX revenue growth has slowed in line with IP PBX shipments, we are expecting IP Centrex and hosted UC service revenue to grow 26 percent year-over-year in 2009," she said.

Right now, IP connectivity services comprise about one-third of total business-related VoIP revenues. That tally is expected to account for 40 percent by 2013, Infonetics projects. The biggest hotbeds of VoIP growth are in North America and Europe, the Middle East and Africa, where service providers are rapidly adding new or expanding existing VoIP services. --Stephen Swoyer