So you need to get hold of a phone number. The obvious solution is to call one of the myriad of 118 directory enquiry services. The problem, though, is that the process will throw up more questions than answers. For when it comes to call charges, consumers who dial 118 will be taking a leap in the dark.
Call a BT 118 operator from a landline, for example, and the cost of your enquiry will be 63p for the first minute - a 40p initial connection charge and then 23p a minute for the rest of the time you're on the line. Get put straight through to the chosen number, and a subsequent 10-minute call will cost you £2.70 overall.
But jot the number down or memorise it and - depending on your phone tariff - the call will be free or just a few pence, after that 40p charge.
On the other hand, ring BT 118 from an Orange mobile handset and the cost is 85p for the first minute, and 60p a minute thereafter.
But use Orange's own 118 service instead and it's 59p regardless of the length of the call or whether you ring from a landline or mobile.
Get put straight through to the number via Orange, and the subsequent cost is 30p a minute. Again, depending on the tariff, you could pay nothing by writing the number down.
Confused? You will be.
The deregulation of the UK's 118 industry in 2003 was designed to create consumer choice. In place of the old flat-rate 192 service, which cost 40p, there are now over 130 numbers fighting for a slice of a £170m market. The most popular are The Number (118 118), with its famous runners, and BT - chiefly thanks to extensive marketing.
To help consumers make sense of it all, two websites - uswitch.com and 118-tracker.com - provide comparisons of call charges, though their focus is on the cost of enquiries made from a BT landline.
Last week the Post Office launched its own 118 service, describing it as an "attack" on high landline charges. It levies a one-off 40p flat fee regardless of call length and doesn't offer a "put through" service (see the table below).
"Providing greater choice was meant to give a better deal, but people have been disappointed," says Simon Carter, head of the Post Office's Homephone service. According to its own research, a third of users think the current 118 services are expensive, he says.
However, the Post Office initiative is likely to be more expensive for mobile users; a Vodafone customer must pay 60p a minute for it.
Most of us use mobiles, of course, but that hasn't persuaded anyone in the industry to help us compare the high, and wildly different, costs of calling 118 numbers from our handsets.
In the first instance, you could ask your own mobile network provider, but it probably won't have the information to hand.
Or you could simply rely on your provider to make the choice for you. However, as 118tracker.com points out, its recommendation might not be based on value for money.
This is underlined by charges for Vodafone mobile users. The company offers a service called Vodafone Directory Assistance, but it actually uses the separate 118 888 number. Customers pay 60p a minute.
However, if these mobile users called OneTel - the 118 service owned by Centrica - an enquiry would cost them almost half that: 35p per minute.
A Vodafone spokesman concedes that prices and offers change all the time, but says the company isn't aware of any major customer complaints about its charges for 118 services.
Another of the problems caused by deregulation is that not all mobiles can call every directory enquiry service.
For example, Tesco's 118 321 service accepts mobile calls from Vodafone but not from O 2.
"Deregulation was intended to provide freedom of choice. However, as not all 118 numbers are available on all mobile networks, choice is being limited," points out Martin Ashfield, managing director of the Performance House consultancy, which owns 118tracker.com.
Mr Ashfield is also chairman of the UK Directory Assistance Association, a fledgling, six-month-old trade body whose aim will be to focus on service, not price.
Meanwhile, Icstis, the watchdog for 118 and premium-rate numbers, which is itself overseen by the telcoms regulator Ofcom, is due to publish a report in March. Here, the emphasis will be on both cost and customer service for landline and mobile directory enquiries.
At the moment, complaints about price and service seem to be on the wane: 80 last year compared with 408 in 2003. But figures for January suggest that this might be about to reverse.
One emerging alternative is free - for now, at least: directory enquiries on the internet; you can try 192.com or yell.com.Reuse content