Watchdog Oftel has slammed four UK telcos for failing to disclose their quality of service figures.
The body called on the companies - Worldcom International, Colt, Global One and cable operator Eurobell - to reveal details soon to existing and prospective customers.
Telcos with more than 5,000 direct and 10,000 indirect connections are expected to offer details of their quality of service to a third party so they can be compared with those from other suppliers. The majority of major companies aleady release details every six months on a direct comparable basis but Oftel said the four companies have failed to take part.
Don Cruickshank, Oftel's outgoing director general, said: "A failure to provide quality of service information puts customers at a disadvantage and may undermine the efforts of the majority of the UK telecomms industry to enhance this already valuable, voluntary initiative to improve information given to customers."
Albert Lee, a director at the Telecommunications Managers Association (TMA) said telcos should make it a priority to report the details to the market, which include customer satisfaction surveys and other performance indicators. Almost half of the TMA's 1,300-strong membership use the data - which is available as a booklet - to help select suppliers.
"The publication is highly influential," said Lee, adding that he was surprised that Worldcom was one of the four named since it is the current holder of a quality award from the association.
In a hastily put together statement from the president of Worldcom International, Colin Williams promised the operator would provide details as from 1 January 1998. Eurobell has also promised to release figures from the start of next year.
The UK's four mobile operators - Cellnet, One2One, Orange and Vodafone - have also agreed to develop a method to measure their quality of service details on a comparable basis. They aim to publish details through the Federation of Communication Services next summer.
Global One and Colt failed to respond by press time.
Cotton seedling freezes to death as Chang'e-4 shuts down for the Moon's 14-day lunar night
Fortnite easily out-earns PUBG, Assassin's Creed Odyssey and Red Dead Redemption 2 in 2018
Meteor showers as a service will be visible for about 100 kilometres in all directions
Saturn's rings only formed in the past 100 million years, suggests analysis of Cassini space probe data
New findings contradict conventional belief that Saturn's rings were formed along with the planet about 4.5 billion years ago