Data cards are the normal way of giving a laptop it’s very own SIM card – thus enabling the user to get online when they’re away from a modem or a WiFi connection, while at the same time providing a useful method pf sending and receiving SMS messages. There are couple of problems with data cards, though. They don’t work with Apple laptops, which never came with the required slot. They protrude and they’re inflexible, so even if they don’t get in the way of your coffee cup there’s a fair chance that you’ll damage the card or the computer when you inadvertently knock it against something unyielding. And in any case the PC Card format is being replaced by a different kind of slot, the Express Card.

Apples have USB sockets, and so does everything else these days. And the USB equivalent of a data card is a bit more flexible in that it is connected by cable, so can be curled out of the way a bit. This is T-Mobile’s version, apparently identical to the Vodafone equivalent (both seem to be made by the same Chinese manufacturer) but obviously provided with T-Mobile software and a T-Mobile SIM. The SIM, incidentally, is inserted into the side of the plastic block – in most data cards it’s embedded and much more difficult to replace.

The modem itself is a small slab of white plastic with a mini-USB socket on one end. Also in the box – one short, one long with a second USB connector in the unlikely event that the thing needs to draw more power than a single plug can provide. Plug it in and a Windows laptop should install it automatically – rather cleverly, the drivers are in the modem, which is recognised in part as a USB disk (try it on an iBook, though, and you’ll have to download the drivers from T-Mobile’s website. Which is what we had to do too, in fact, since our laptop declined to recognise the presence of any software on the modem).

The big deal is the SIM, of course, and its access to T-Mobile’s Web’n’walk service — HSDPA speeds for a very competitive price. The USB modem is free on an 18-month Web’n’walk Plus plan (contract price £24.68 a month).

The T-Mobile USB Manager software isn’t quite as slick as Vodafone’s, being more geared to performance statistics, but it will do the same kind of thing – make internet connections, send and receive texts, maintain a phonebook, and more.

• The best HSDPA deal on offer in the neatest type of package