Britain's busiest telephone number is 0845 7484950, and it costs so much to run that the train companies want to set up a call centre in India. But although three-quarters of rail inquiries are still made by phone, there are better ways to research fares and buy tickets.

For basic timetable and pricing inquiries, www.rail.co.uk is the obvious place to go: but in order to actually buy a ticket, you will have to choose between www.thetrainline.com (owned by Virgin and Stagecoach) and www.qjump.co.uk (which belongs to the National Express group). In theory, both sites carry exactly the same fares.

Tickets for the Gatwick, Heathrow and Stansted Expresses can be bought online at their own sites, but there's no saving to be made unless you buy a carnet.

In an effort to find out how the online ticketing services dealt with a particular journey, I invented a day trip from London to Birmingham - leaving on the 0700 from Euston and returning at 1715. (This is a Silverlink route, too. Rail Enquiries explained that it was cheaper but took longer - thetrainline.com ignored it altogether.)

It used to be a truism of rail ticketing that a return was cheaper than a single. On some long-distance routes, that's still true. But as National Rail Enquiries pointed out, Virgin's advance fares on this route are all singles. Were you to queue on the day of travel and ask for a return to Birmingham, you'd probably be sold an open return for £93. Buying two singles - which may commit you to specific trains - costs less than half.

Worryingly, there was a discrepancy between the information provided by qjump and thetrainline.com, with the latter offering "Business Advance Standard Returns" - not a first-class ticket, but an "advance purchase standard class product for business customers". That, said qjump, was because it was a new ticket which had only just been released by Virgin. The Rail Enquiries number didn't mention it at all. And watch out for thetrainline.com's lamentable practice of automatically adding insurance to the cost of the trip.

The conclusion is clear: train ticketing is becoming steadily more complex. If you want to reduce the amount of money you spend on them, don't rely on turning up at the station: do your research online.