There have been rumors about circumventing that annoying SIM lock. As Geohot stated (read here), modifying the 3G baseband will not be an easy task. Because this task still needs to be solved, some guys thought bypassing simlock by using Proxy SIMs might be a good idea for 3G iPhones as well.
Differences between 2G and 3G iPhones
For 2G iPhones Proxy SIMs worked very good, because only the iPhone checked once at startup, if the SIM is from a supported country and carrier. SIM Proxys faked this first answer only and gave control back to the real SIM card, which has been asked for all details (IMSI, Country Code etc.) again. The then gotten details have been used to transfer to the network and to try to log in.
After investigating in the Proxy SIM possibilities for the 3G iPhone the iPhone Dev Team (namely: _ZF) stated that in contrast to the behaviour with 2G Proxy SIM solutions, the behaviour of 3G basebands is like transferring the first gotten IMSI code to the network. This means: for 3G iPhones the Proxy SIM will fake a test IMSI card and the iPhone will send this test IMSI code to the carrier to log in.
Legal and technical issues with 3G Proxy SIMs
Although applying methods like this in order to unlock the iPhone 3G is most likely illegal in many countries (because it violates contract), members of the Hackint0sh forum have played with Proxy SIMs on different networks in the world.
As expected the results are disappointing. Besides the questionable legal status of those operations there have been heavy technical problems.
- First being support for 3G. Currently no Proxy SIM supports it. You can only surf the net and check emails and so on using 2G/EDGE/GPRS technology – means same functions like with a 2G iPhone.
- Second being the problem of the IMSI fake ID. At least european carriers seem to have applied security precautions to their networks. After some time you will be logged out of the network. This may take some minutes to some hours.
- Third being the problem that people reported the Proxy SIMs are still too thick. Several people broke their trays when trying to release the tray from the iPhone.
Types and Brands of Proxy SIMs
Tested cards include:
Currently none of these Proxy SIMs work reliable (cf. iPhone Wiki). Our recommendation is simple: keep on waiting, the iPhone Dev Team will make it sooner or later. In case you cannot wait, get yourself a factory unlocked iPhone 3G from one of the countries supplying them (see country list here) and save precious life time.