NO SIM display by iDevice

One can freak out when one puts a sim into the iPhone and it displays NO SIM. Even when SIM is ejected, it still says NO SIM.
there are three main reasons listed below for this issue.

I have been faced with these problems and i have helped in solving it in the 3 circumstances presented below.

Reason 1: Invalid or Unsupported Sim card
sometimes when an invalid sim is inserted into the iPhone, it can display NO SIM. Although, at first it will attempt to read the sim. if it detects an invalid SIM It will refuse to detect and read the SIM. Consequently, NO SIM is displayed after a few seconds

Solution: The solution to this is to use a supported SIM card and if you don't have that, then you will have to jailbreak and or unlock your phone to accept other SIM cards that were not initially supported.

Factory unlock is the best unlock solution out there for your devices. You can visit www.officialiphoneunlock.co.uk, www.imeiunlockiphone.com for this purpose.However, software and hardware unlock solutions also exist. Read my other blogs for more info

Reason 2: Error in downgrading iOS
There are times you upgrade to a higher firmware and iOS only to find out that you can't unlock or jailbreak your device on that particular firmware of iOS. So you decided to downgrade your iOS and firmware especially for iPhone 3GS. Even though the downgrade was successful, the baseband can become corrupted and eventually the phone will not be able to detect sim. Consequently, it will display NO SIM even if sim is not inserted

Solution: To solve this, you will need the following items: Redsn0w 0.9.11b1 and your iOS ipsw. 5.1.1 for iPhone 3GS, alreay saved blobs for iOS 5.1.1 if you want to restore to that iOS version
Make sure you have updated your device's iOS to 5.1.1 whille preserving baseband.

1. run downloaded redsn0w and plug in your iPhone 3GS
2. go to Extras and click on Select ipsw
3. Select the iOS ipsw you downloaded. it will ask you if you have a new boot rom or old boot rom. To find out which boot rom you have, read other of my blogs.
4. Click on Yes if you have a new boot rom
5. Go back and Jailbreak your device
6. After jailbreak, check "install ipad baseband" also chech "install Cydia" an click 'yes'
7.put your device in DFU mode by following resn0w instructions
8. make sure its plugged in firmly and allow redsn0w to work its wonders by flashing babseband.
9. After the process, click done.
10. If your device is stuck on apple logo for too long, dont panic
11. Run reds0w and click on Extras again and repeat steps 3 to 5
12. Now, after this jailbreak, put your device in dfu mode again. Click Extras and then click on "Just Boot"
13. Once your device boots into the phone, make it into an untheter jailbreak: go to Cydia and install Rocky Racoon
14. Unlock the device with Ultrasn0w
This will fix the issue.
For further assistance, drop your comments.

Reason 3: Faulty or Dirty sim reader
In this case, y ou have a valid sim and your baseband is good. However, the sim card reader has issues. it could be dirty or just faulty.

Solution: To fix reason 3, you will have to open up your device. ifixit has a guide on that here: www.ifixit.com/Device/iPhone

All you have to do is open up the sim reading compartment, take isppropyl, methanol or nail paint removal to clean the compartment very well. Also, clean the chip area of the sim very well.
Couple the phone back and insert your sim into the sim tray. insert the sim tray into the phone and see your network bar showing up

Am sure these tips will help you resolve your issues. Drop your comments and lets hear how much you were helped