Iphone unlocked but showing no signal on all networks apart from original carrier!

It sounds as if the device is not unlocked. What other troubleshooting have you tried? If you restore the device as new in iTunes with the Three SIM installed do you receive the Congratulations, your phone is unlocked message? If not, then the device is still locked.

I'm not sure what a PAC code is, but whatever it is has nothing to do with unlocking an iPhone. The only legitimate way to unlock an iPhone is for the carrier it is locked to request that Apple mark the phone as "unlocked" in their database. Any other way requires hacking the phone, which frequently doesn't work or causes other problems. So the first step is to call Three and ask them if they have unlocked the phone. If they have not, ask them to unlock it. You can also call Apple or visit an Apple store and ask if they phone is unlocked. They can check. If it is unlocked you may have to connect the phone to iTunes and Restore iOS using iTunes, setting it up as a New phone (you can restore your backup later if this is successful). If the phone has been properly unlocked iTunes will display a message telling you so.

Also, if the phone has NOT been unlocked you will see a message that says "Invalid SIM" when you insert a SIM from a different carrier. If you do not see this message then either the SIM is bad or is not iPhone compatible, or the phone has been hacked to unlock it. In that case all bets are off.

They don't know what they're talking about. Call Apple and give them the serial number. They can tell you if it's unlocked and what carrier it's locked to if it's not.

taymur_ wrote:

Three told me that the phone is unlocked, they said once you enter a new sim. You'll need this PAC code, so I'm guessing it is pretty important when unlocking an iphone. Also, it does not show 'Invalid SIM' like it is supposed to, it just shows 'No Service' on the top left corner when I use a sim from a different carrier :/ I might just end up visiting an Apple store, if i do not find a solution on here

No, you don't need a PAC code. Three doesn't know what they are talking about. Other phones unlock with a code; iPhones do not. However, you DO have to either erase the phone or restore iOS after the phone is unlocked so it will query the Apple server to update its lock status.

To erase the phone:

• Go to Settings/iCloud, tap Backup, and backup the phone to icloud.
• Go to Settings/General/Reset and tap Erase All Content and Settings.
• When the erase completes restore your iCloud backup.

To restore iOS:

• Make sure you have the latest version of iTunes (12.3)
• Connect the phone to your computer
• Click on its icon in iTunes
• Click Backup
• Click Restore - you should see a message saying the phone is unlocked near the end of the process.
• When the restore finishes you can restore your backup.

Deleted. This post was not relevant after the OP made another post.

taymur_ wrote:

Okay guys, I phoned up apple and they simply said restore the phone through itunes. I did this, and it came up with a message 'Congratulations, your phone has been unlocked'. I was all good to go, waited for my phone to load up and STILL THE SAME THING! It says 'GiffGaff' but it is showing not signal strength

Then there is something wrong with the GiffGaff SIM.

Earlier you said you restored the phone, but not through iTunes. But iTunes is the only legitimate way to restore an iPhone. So how did you do it if not through iTunes? While there are 3rd party tools that can hack an iPhone and possibly restore it, all of them corrupt system data in the phone, so if you used one of them that is most likely the cause of the problem.

If the SIM isn't activated you will see a "no signal" message.