Using a 'SIM unlocking attachment' or Turbo SIM.
Last updated 27-APR-11Unlocking SIMs, Turbo SIMs, Unlock SIMs and Smart SIMs (as they are variously called) are tiny sleeves you place between your SIM and your phone, that "trick" your phone into thinking your SIM card belongs to a different network.
How is it possible for something to fit in there? I hear you ask? These devices are surprisingly thin and older Turbo SIM models require you to cut your SIM in order to make this possible. However, it is by no means a comfortable fit even if you pull this off. Getting the device in there is notoriously fiddly but can be done. Because it's such a tight fit, we hear accounts of people who've damaged their phones and/or SIM card readers in the process when using this method, so do bear this in mind. There are also reports regarding their reliability, and additional configuration may be required.
This option is included in our list even though it doesn't technically unlock your handset. How is this possible? What these tiny devices actually do is mask your SIM's operator's identity. This means that you can use it and then remove it and no underlying settings will change on your phone. Neat, no?
There are many good things about this unlocking option. One big benefit of these attachments is how cheap they are compared to other methods. You can buy them on ebay for as little as £3 including delivery. Another big benefit is that they don't actually unlock your phone, so don't invalidate your warranty
In terms of usability, some Turbo SIMs need to be configured to work with your make and model using a SIM card reader by connecting them to your computer. Others require you to enter a code when you switch your phone on to tell the device which settings to apply.
However, these devices have fallen out of "fashion" due to their unreliability, fiddlyness and the low range of compatibility. The problem lies in the fact that they need to be specifically configured to work with new phone models, rather than working out of the box with any SIM. This means that they are unlikely to work with the latest models, and you might have to wait up to 6 months for an up-to-date Turbo SIM to become available.