Monday, April 4, 2011

Unofficial Gevey FAQ

This post is not a statement on the legal/moral debates surrounding the use of Gevey SIM or similar means to pseudo-unlock the iPhone 4. It is purely to help those who are experiencing issues with these products and failed to get any support from the resellers:

Q: I get "No SIM" after I put my SIM card in the phone with Gevey.

A: Assuming both your SIM and Gevey are working, the underside of your MicroSIM may be touching the chip on the SIM interposer and shorting it. Cut away some more to give enough clearance between the SIM and the chip. 

Q: I had to enable "Data Roaming" in order to use mobile data, would this incur a lot of roaming charges?

A: No. Data roaming needs to be enabled because the way this exploit works, your network will always bill your call/SMS/Data correctly as before.

Q: My caller ID is not working and my SMS threads are fragmented, why?

A: The "unlock" causes the phone to use 001 as the default MNC, which has no matching country code and your phone fails to map caller ID to your country. There are many ways to get around it, e.g. manually adding the country code to every number in contacts, adding custom carrier bundles for 001/01 or a network reset/full reset. A more consistent method is to open /System/Library/Frameworks/UIKit.framework/PhoneFormats/UIMobileCountryCodes.plist and add the highlighted part:

Replace %Your Country Code% with ISO3611 alpha-2 country code for your locale: nz for New Zealand, jp for Japan etc.

Q: My data connection dropped out and I cannot get data on 2G or 3G, I have checked my APN settings and they are correct.

A: Use your SIM in any unlocked phone with GPRS functionality once to re-establish data session; expect to do this on a regular basis.

Q: I have full signal bars and I can call normally; but when other people call me it says number is not listed or goes directly to voice mail. 

A: I have explained earlier that you need to obtain a TMSI from the network to connect. Theoretically the TMSI will stay with your number as long as your phone remain connected, and when you move between cells it is passed to the next base station so you don't have to call 112 again.

Nevertheless the carriers usually configure their network to refresh TMSI periodically for security and administrative purposes. It has also known that some cells, particularly the ones serving train stations and major road intersections, require a TMSI refresh following a hand-off(Because users tend to move in and out of coverage very rapidly, TMSI reuse cause unnecessary delays).

Your phone will not recognise the refresh because it is for your original IMSI and your phone is still on the test IMSI starting with 80900101. You can call because your old TMSI did not really expire and is hence accepted, however the network is unable to locate you because it uses the new TMSI which has never been updated on your phone.

Out of all the issues with the Gevey this one stands out as the most deleterious, and there is nothing you can do to stop it from happening. In fact you cannot even tell because the signal bars will appear normal and you can dial out perfectly fine. The only way out is to restart the phone and start over to match the TMSI.

Q: Help, my SIM is stuck and I can't take it out!

A: Do not force your SIM tray if this happens, you are going to cause more damage. Push it all the way back in and tap the phone a few times, gently but firmly, against the palm of your other hand or any soft object e.g. a large pillow. If this had failed to free the SIM tray you will have to take your phone for repairs. (If you are feeling particularly adventurous, you can do it yourself by following this excellent guide created by iFixit; however do this at your own risk and be prepared to lose your warranty because one of the screws cannot be accessed without breaking the warranty seal)

Don't get me wrong and think I am scaring you; this can happen to anybody but it is more likely with the extra thickness provided by the interposer.

Update 1:

Q: My battery level seems to go down very quickly now...

A: Now there are two possibilities, one is that you are simply not used to the i4 acting more than an iPod. cellular transmission can use a lot of battery power, especially on 3G and whenever the reception is poor. However if your data usage listed under Settings/General/Usage seems to be too much AND you have hacktivated your i4 (activated using limera1n/redsn0w etc) then chances are your problems is real.

If you never used and does not need push notifications, you can simply delete /System/Library/LaunchDaemons/ and restart your phone. Any battery drain caused by hacktivation will cease however push service itself will also be gone. Alternatively use many of other solutions available (PushFix, PushDoctor, SAM) that all fix the problem to a varying degree.

Q: Which carrier bundle should I use?

Your default carrier settings is stored under CarrierLab.bundle, which is actually not that bad since it allows free editing of the APN settings. If you need to get VM or VVM working, Wortel's patch has to be installed first before you can edit the bundle.

Carrier Logos should go to your actual carrier's folder, not CarrierLabs since your phone will be "roaming" on your actual network.