Ofcom has proposed a cap on the price of 118 directory inquiries at £3.10 for a 90-second call.
The communications regulator said it had been concerned about the rising cost of directory inquiry services.
In May last year it launched a review to examine the rising cost of calling inquiry services and ensure prices were transparent and fair.
However the review found that in addition to the high prices that some directory inquiry providers charge, there was also a lack of transparency and awareness of their cost.
Ofcom found people were often paying much more than they expect.
As a result, it is proposing to cap the cost of directory inquiry services at £3.10 per 90 seconds, which would bring prices back to 2013 levels.
An Ofcom spokesman said: “We’re concerned about rising prices for directory inquiries, and callers paying much more than they expect.
“So we’re taking action to protect consumers by proposing a cap on the cost of 118 numbers.”
Ofcom’s consultation will run until August 22 with a decision due at the end of the year.
Alex Neill, Which? managing director of home products and services, said: “A lack of clarity around how much it costs to use a premium-rate phone number means people can find themselves being hit in the pocket when the next phone bill arrives.
“We hope Ofcom’s consultation will lead to firm action to ensure that prices are transparent and fair for all consumers.”