As broadband connectivity spreads around the world, so too do the value-added services of VoIP and IPTV.

VoIP is a genuinely disruptive technology and has changed the telecommunications landscape. IPTV, on the other hand, which requires considerably more bandwidth and technical know-how from service providers, is still in its infancy, according to eMarketer's report Broadband Services: VoIP and IPTV.

Pureplay VoIP provider Vonage was the single largest operator in the US at the end of 2006, but this is unlikely to last. Cable MSOs ComCast and Time Warner are growing their VoIP subscriber bases very quickly and will surpass Vonage in 2007.

eMarketer estimates that the number of US VoIP subscribers will rise from 9.8 million at the end of 2006 to 41.3 million by the end of 2011. VoIP subscribers will account for over one-third of all US landline subscriptions in 2010, up from 10% in 2006.

Due to slower than anticipated rollout and take-up of IPTV in the US, eMarketer has revised its estimates down and now forecasts only 4.8 million IPTV subscribers in the US in 2011, up from 300,000 in 2006.

"Early indications suggest VoIP will be very popular worldwide simply because VoIP calls are cheaper," says Ben Macklin, senior analyst and author of the report. Meanwhile, IPTV requires bandwidth, favorable regulatory environments and favorable TV market dynamics, he says.