The cost of calling directory enquiries on 118 118 has rocketed over the last few years.
Since 2015, the price has gone up by 50%, and it now costs an eye-watering £9 for a one-minute call.
The service is used mainly by businesses, and by elderly people who may not be comfortable using the internet to find the number they want.
But what most people don't realise is that there is a much cheaper alternative - and it's run by the same company, The Number UK.
If you call 118 811, your enquiry will cost just £1 a minute, plus your network provider's access charge. You won't, though, get the number texted to your phone, and you'll only be able to ask for one number at a time.
And if you don't mind an automated service, The Number UK even offers a directory enquiries service that's completely free - just call 0800 118 3733. You'll have to put up with a 20-to-30-second advertisement at the beginning and of the call, but you won't have to pay a penny.
"The fact that you can get the same service for £1 but this information is hidden away should tell everyone what they need to know about how these services work."
Two years ago, regulator Ofcom changed the pricing model for numbers beginning with 118, 084 and 087, ordering companies to make their pricing model clearer.
But earlier this year, it said it still wasn't happy and was carrying out a review.
"Ofcom has been monitoring the costs of the more expensive services, which have risen significantly in recent months as fewer people use these services," it says.
Other providers include Yell on 118 247 and BT on 118 500, with both charging £2.75 per call, plus £2.75 per minute.