No, we couldn't work it out either, but here's the story of a valiant attempt to define value for mobile email money ...

It is a rare luxury to keep hold of any piece of IT equipment long enough to gain a proper understanding of its merits, but for the last few months I have been fortunate enough to travel far and wide with the Orange Business Everywhere Data Card as a companion.

I say fortunate, because it has proved genuinely useful, helping me turn otherwise dead time spent sitting in stations, airports and other transport hubs into windows of productive opportunity through the magic of mobile email and Internet access.

The big question, as yet not completely answered I'm afraid, is whether signing up to a high speed data packet access (HSDPA) service offering a theoretical maximum downstream bandwidth of 1.2Mbit/s, which defaults back to either a 64Kbit/s general packet radio service (GPRS) or EDGE link whenever it cannot find a HSDPA signal (which is often) is actually worth the price premium you pay rather than attaching yourself to the nearest WiFi hotspot whenever necessary.

The Sierra Wireless Aircard 850 Orange provides as part of the Business Everywhere service costs £115, including an extra strength antenna that clips onto the lid of the notebook PC.

Using the service from IT Week's office in Soho, central London with the clip on antennae, I recorded downstream speeds of 507.33Kbit/s downstream and upstream speeds of 350.9Kbit/s upstream - more than adequate for reading email and web browsing, although some pages take more time than others to download and transferring large files can be problematic.

Trying the same test again with the standard antenna attached to the data card yielded far less impressive results though: 23Kbit/s both up and downstream, much less than GPRS through the signal indicator showed a strong 3G connection, and only really good for reading text based email.

One benefit I had not anticipated was using the Orange mobile data network as a backup to keep me connected from home when my broadband ADSL line goes down, which it does too frequently for comfort.

Living in a small village in the middle of nowhere the Orange mobile signal in my house is quite weak, which means the network's data transfer speed fell a long way short of 56Kbit/s dial-up. But then I suppose that in any situation where equivalent wired or wireless access is unavailable, any connection is better than none at all when you are desperate to access your work email.

If there is any complaint at all about the card, inevitably it centres around cost. The availability of international roaming connections actually turned out to be much better than I’d hoped for the countries I visited during the test (apart from China). It was rare for me not to get some sort of signal in any of the other places I visited, mostly Western Europe and US, though it was usually GPRS rather than the faster HSDPA or EDGE.

The trouble is, most of the locations I used the card in (which tended to be airports and hotel rooms) were also served by public access WiFi hotspots. And cost comparisons of using the Orange Business Data Card service compared to just latching on to the nearest WiFi hotspot are very hard to make.

All Orange could tell me is that during the period of 24th April to 23rd May, I sent and received 55MB of HDSPA/GPRS data which cost me about £50, which may or may not have exceeded my monthly data allowance depending on which monthly tariff I was theoretically signed up to.

So whether this compares favourably to using WiFi hotspots, which generally deliver more bandwidth but are charged for by the minute rather than the megabyte, for the same amount of data in a monthly period is difficult if not impossible to assess on the evidence available.

That said, the fact that Orange's international data roaming charges range from £5.50 to £6.50 (the tariffs are listed at the following url: http://www.business.orange.co.uk/servlet/Satellite?pagename=Business&c=OUKPage&cid=1044131837716) indicate that WiFi might be the cheaper option if you do most of your mobile web surfing from outside the UK.

All in all, as clear as mud, so no change there as far as international roaming charges are concerned. Let's hope the EC can deliver on its promise to make mobile charges in general more transparent.