A couple of months ago, I met Brad Feld in Paris who at the time wrote a blog post about the difficulties of getting a prepaid data sim card without a monthly plan in France.

Consequently I assumed this would be easier in the US. Well, I was wrong. Pretty much like anywhere else in the world, it turns out to be really hard to just get a sim card of a national carrier that gives you data – prepaid and usage based – say $30 for 1 GB = no monthly plan, no contract and no need to buy a mobile phone that locks you in with a specific carrier.

After two days of trial and error in different stores and different carriers, here is what worked:

1. Go to a T-Mobile store. Others may or may not work, but we weren’t successful in the others we tried…

2. Ask specifically for a sim card only. You wanna buy it for around $10 which is the activation fee of the card. Store personnel will try to be helpful and sell you a phone and a monthly plan and all that other stuff you don’t need if you already have a phone – or like in my case a wireless (sim card based) router like the huawei or mifi. So be patient and expect the conversation to take some 5-10 min for the other person to understand what it is that you really want :)

3. Put the card in your mobile phone or device, it should get the signal of TMO / T-Mobile. If it doesn’t, something is wrong with the sim card or your device. Don’t proceed until you have a basic GSM signal at least mentioning the name of the carrier.

4. Now the tricky part comes: Every mobile device, whether phone, router, iPad or usb stick, will have a so-called IMEI number. Without store personnel entering this number of YOUR device in the backend of the T-Mobile system and associating it with the sim card you’ve just purchased, your card will be worthless and data won’t work.

However – the screen of T-Mobile’s backend doesn’t allow store personnel to enter your ID just like that. In fact you need the good will of the staff to scan a T-Mobile mobile data device (which then activates your sim card with THAT device – which of course you won’t purchase) first. Only after this is done, they can get to the backend screen where they can change the IMEI to that of your actual device.

Good luck! For us it worked fine – expect the whole process to take 20-30 minutes.