Vodafone is supporting CityFibre's legal bid to strengthen the rules on fibre broadband advertising.
CityFibre this week confirmed it is taking the Advertising Standards Authority (ASA) to court over its decision to allow copper-based broadband to be advertised as "fibre".
The move came after the ASA ruled last year that using the term "fibre broadband" in adverts for part-fibre services is not "materially misleading",, as consumers regard it as a "shorthand buzzword to describe modern, fast broadband".
However, CityFibre is maintaining that consumers are being "actively misled" if adverts for copper-based products are promoted as "fibre".
This, it said, is because the presence of copper in a part-fibre network results in slower download and upload times, whereas full-fibre services are capable of achieving Gigabit speeds (1,000Mbps) and are far more reliable.
The organisation has therefore filed for a judicial review of the ASA's ruling, on the grounds that the research and logic that led to the decision was "fundamentally flawed".
Vodafone, which recently entered into a long-term strategic partnership with CityFibre, has backed the move, saying customers should "absolutely get the service advertised and its description should be clear".
"That is why we have led the market with the introduction of guaranteed broadband speeds on our new Superfast packages and we were the first to abolish line rental," a spokesperson commented.
"Fibre should mean fibre all the way to people's homes and we look forward to offering customers exactly that later this year in partnership with CityFibre."
CityFibre's decision to take action has also been hailed by Gigaclear, as it believes that if consumers are not told how full-fibre is different from part-fibre, they are being "blinded to the fundamental capabilities of services on offer".
Matthew Hare, Chief Executive of Gigaclear, commented: "With part-fibre, the consumer is wholly reliant on the quality of the copper or other technology that is connecting them to the fibre backbone."
Mr Hare went on to note that the UK lags behind many other European countries when it comes to full-fibre broadband, as the technology is available to just one million British properties at the moment.
He stated that while the government has "communicated the importance of full-fibre networks for our economic future", the telecoms industry and the ASA must now respond.
"It’s time to educate consumers in a clear and concise way, to ensure they have the knowledge to choose the service they want," Mr Hare added.