As of 2017, the ThinkPad laptop has a German SIM for data. This comes with 100MB (!) of "fast" internet per month, and then gets rate-limited for the rest of the month. For SSH/textual use, it is much the same before or after the cut-off.
As a back-up, I have a British Three SIM, but now on the Granny tariff instead of the unlimited all inclusion "One Plan" offering. Thanks to the European Union roaming caps, it is now normally cheaper to roam when travelling, than buy and use a local SIM!
As of 2013, I have two SIMs for 3G data, with the built-in WWAN card on my ThinkPad. I use SSH tunneling to gain compression and reduce usage in both cases.
Back in the old days…
Well, I got an unlocked Sierra Wireless Aircard 750 off Ebay (PCMCIA GSM+GPRS datacard). Then I needed a SIM and a network connection to use it with; in the UK there are two ways of signing-up the first being contracts paid in arrears (at the end of a month) for the cost of the `line' plus the sum of the calls made in the previous month. The second method is pre-paid systems, where you signup with a mobile phone-company and purchase `credit'; that is, you pay up front for a certain volume of calls and need to ``top-up'' when you pre-paid credit runs out.
There are a number of caveats; with the contract system a data-tariff is often available only on top of an existing voice contract. This means that you may be paying upwards of £20.00 per month (£15 voice plus £5 data) before you even download a single byte of data; with a PCMCIA card that can't even make voice calls this doesn't make sense! Vodafone are the only people in the UK to offer a data-only tariff and this costs £5.00+VAT (£5.87) per month. On the pre-pay side one gotcha is that some networks require you to top-up with £10.00/month (eg. You need to spent at least that per month or your phone gets cut-off). Pre-paid GPRS costs are from £4.00-£10.00/MB).
Pre-paid Orange PAYG (Pay-As-You-Go) had the cheapest per-MB rate for GPRS and no limitation on ``roll-over'' (being able to use your credit over as long a period as you need). I wasn't keen on signing up for a 12month contract as I'm hoping/expecting 3G (Next-generation UMTS) data-rates to start being affordable in early 2004. Much to my surprise, pre-paid came out cheaper for the usage I'm expecting to use. Here are the figures I'm working with; I've already discarded all the other networks' offerings as they didn't work-out cost effective:
|£20.00||£0.00||0 MB||£4.00||Orange PAYG|
|£0.00||£5.88||0 MB||£2.35||Vodafone Contract|
To further complicate matters. Firstly, the Vodafone offers are quoted without VAT, hence £2.00→£2.35 and £5.00→£5.88. Secondly, I purchased a new Orange PAYG SIM on Ebay for £9.75; including delivery and which came with £1.00 included (effectively £8.75). Thirdly, if you buy greater than £50.00 worth of PAYG credit Orange give you 10% on top, bringing the effective cost down from £4.00/MB to £3.64/MB. Revised costings:
Adding together the rental cost (or the one-off cost of the SIM) and the price per MiB over a 12month period:
Calculation: 8.75 + 3.64x = 70.50 + 2.35x → 1.29x = 61.75 → x = 47.86
≤ 47.86 MB/year (< £182.96): Orange PAYG is better value
≥ 47.86 MB/year (> £182.96): Vodafone Data-only Contract is better value
Occasionally (eg, when downloading a big file) it actually makes better sense to dialup at 9600-baud than use GPRS. Orange have three variations of PayAsYouGo. After doing the maths I reckon that although I thought Talk&Save works out at quite a lot for the initial three minutes on a particular day. Talk&Save is the best value for GSM dialup (for long download periods when GPRS stops competing).
|GSM Dialup||Talk&Save||FixedAllDay||ChooseOnPeak ChooseOffPeak|
 Maximum difference between Talk&Save and FixedAllDay
 Talk&Save becomes the cheapest after 6minutes
 After 12minutes of dialup, Talk&Save becomes even cheaper ``OffPeak''