VoIP suppliers could eventually have to provide access to emergency services as part of a regulation under consideration by the UK telecom regulator.

Ofcom has opened a consultation that will run through September 20 to get feedback on the plan and expects to make a decision before the end of the year, said Simon Bates, Ofcom spokesman. If the regulation is adopted, certain providers would have three months to comply, he said.

Now, only 64 percent of British households using VoIP services have access to 999, Ofcom said.

Also, 78 percent of VoIP users surveyed by Ofcom who can't call 999 didn't know they couldn't. The UK had 2.4 million VoIP users at the end of 2006.

Providing emergency access would cost about £0.90 per household per year, Ofcom said. Some VoIP providers, such as BT and Vonage, already provide emergency access, Ofcom said.

"The large providers have seen the writing on the wall," Bates said.

If adopted, the regulation would apply to two types of VoIP services - so-called 'VoIP out', where the customer can call from one computer to another as well as to a land line but can't receive calls from the PSTN (public switched telephone network), and 'full-service VoIP' where calls can be made and received from the PSTN, Bates said.

The Internet Telephony Services Providers' Association, an industry group that has advocated a 'light touch' approach to regulation of VoIP providers, was not immediately available for comment.

In the US, the Federal Communications Commission has banned companies from advertising VoIP services if they do not allow people to call emergency services.