The use of voice over internet protocol (VoIP) in Europe has risen over the past three years, new research has indicated.

According to data from TeleGeography, 34.6 million users across Europe and the UK had subscribed to VoIP services at the end of 2008, up from the six million that had registered in 2005.

As a result, over 24 per cent of fixed-line telephone subscribers are now using VoIP technology, despite the fact that the sector's service revenues of €4.1 billion (£3.49 billion) are still less than the €36 million generated by their non-internet based counterparts.

Analyst at TeleGeography Paul Brodsky explained that fixed-line telephone services are no longer the "cash cow" they once were.

"Voice is increasingly just a loss-leader, used to sell broadband and video services," he remarked.

Figures collected by the research company showed that many telephone companies have opted to introduce discounted VoIP services and cut fixed-line prices, resulting in aggregate revenues falling to €39.9 billion last year - a figure that is expected to decrease to €26.2 billion in 2013.

Gartner recently released a report predicting that mobile VoIP applications will have increased in popularity by 2017 with the introduction of 4G networks expected to contribute to growth.