The UK telecoms regulator has, as expected, ruled that customers must be able to call the emergency services using voice over IP (VoIP).

Ofcom has ruled that all VoIP providers that connect to the UK public switched telephone network (PSTN), have to modify their systems to allow 999 or 112 telephone calls to be made, if they don't already do so.

"As new voice services develop and become more mainstream, regulation must evolve too," said Ofcom chief executive Ed Richards. "In the future, consumers will be confident that, if they can make calls to ordinary national numbers using their VoIP service, then they will be able to call 999 or 112 in an emergency."

In the United States, the Federal Communications Commission has already banned companies from advertising VoIP services if they do not allow people to call emergency services. In the UK, suppliers including Vonage and BT already allow calls to the emergency services from their VoIP offerings.

According to Ofcom, only 64 percent of British households using VoIP services have access to 999. Also, 78 percent of VoIP users surveyed by Ofcom who currently cannot call 999, mistakenly thought they could. The UK had 2.4 million VoIP users at the end of 2006.

Suppliers have until September 2008 to upgrade their systems, around six months later than originally planned.