Compiled By Jill Jusko It's the beginning of the end for conventional telecommunications networks as consumers increasingly turn away from secondary telephone lines in favor of wireless service and broadband, says Forrester Research. The Cambridge, Mass.-based research firm says more than 5 million American households will migrate to mobile telephones and high-speed broadband networks for their primary connection by 2006, costing the telecommunications industry almost $9 billion. Wireless will gain 11% of household spending in the next five years, and the average number of mobile phones per home will grow to 2.2, the firm forecasts. By 2006 broadband will take revenues from fixed-line providers and dial-up ISPs (Internet service providers) when more than 50% of households subscribe to high-speed Internet access for voice and data. "Broadband providers will ... take voice business away from traditional service providers as they begin to offer voice over IP [Internet protocol] service in 2002," says Charles Golvin, senior analyst at Forrester. "By 2006 these packet voice offerings will displace 4.26 million traditional lines and nearly $1.5 billion in annual revenue."