Internet phone firms have been told they must ensure customers can use their services to call emergency numbers.
Industry regulator Ofcom has given voice over internet protocol (Voip) services until 8 September, 2008 to ensure callers can connect to 999 and 112.
The number 112 link to emergency services anywhere in Europe, including the UK.
Ofcom warned that consumers who mistakenly thought they could use their Voip service to call emergency numbers would face a critical delay if they then had to find an ordinary landline or mobile phone.
Ofcom’s new rules apply to Voip services where users can make calls to geographic landline numbers but not receive them, and to ‘two-way Voip’ where users make and receive calls to and from geographic landline numbers.
Ofcom Chief Executive Ed Richards said: ‘As new voice services develop and become more mainstream, regulation must evolve too.
‘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’.
Voip calls work by sending the caller’s voice over the internet as packets of information in the same way as photos, text and other data.
The service is now offered via PCs, home phones and mobiles.
It is increasingly popular in the UK, with the industry predicting up to three million users will be signed up by the end of this year.