One in 10 broadband subscribers in the US will be using broadband IP telephony within four years, analysts have predicted.

In-Stat/MDR has estimated that there were only 114,000 subscribers using broadband to make Voice over IP (VoIP) calls at the end of 2003.

Unlike older VoIP services, broadband IP telephony allows for both inbound and outbound voice traffic and can function as a primary voice line, something likely to drive rapid adoption, according to the analyst.

In-Stat/MDR predicted that 10.3 per cent of all broadband subscribers will use broadband IP telephony by the end of 2008.

While this service targets primarily consumers there are some business service offerings, but the analyst warned that the nature of the service limits it to the smallest of offices needing few voice lines.

Daryl Schoolar, a senior analyst with In-Stat/MDR, warned that there is still regulatory uncertainty in the US.

"Until all of the regulatory issues surrounding broadband IP telephony are resolved, potential investors will be wary of putting money into a service provider that could lose its entire market advantage due to an unfavourable ruling," he said.