VoIP users in America have expressed their dismay after their service provider SunRocket went out of business without warning.

Some 220,000 customers were left either without service or with the possibility it could cut out at any time by the first significant collapse of an IP telephony company.

Concerns have been raised over how quickly the company shut down its operations as these may have endangered customers, for example if they needed to make an emergency call.

But measures to improve the regulation may now take place in the US to make clear what the responsibilities of VoIP providers are and educate customers as to the risks involved with dealing with certain providers.

John Nakahata, former chief of staff for the Federal Communications Commission and now a Washington lawyer focusing on telecommunications, told the New York Times: "Ultimately, the consumer has to learn to factor in, how stable is this entity I'm entrusting with my phone service?"

But IP telephony in the US is still booming, with some 10.8 million subscribers at the end of March this year, according to market research firm TeleGeography, nearly double the 5.7 million of a year earlier.