The report said that according to the research firm's report, robust sales of Class 4 trunk networks drove the market for next generation network equipment in 2005.
However, Dell'Oro Group predicts that Class 5 subscriber solutions will drive growth in the future as VoIP services gain popularity among both consumers and businesses.
"As service providers race to offer new VoIP services, most next generation networks will overlay the existing circuit switch networks," Steve Raab, director of IP telephony research at Dell'Oro Group, was quoted as saying.