SIM won't work in iPhone

Question

Level 1

10 points

SIM won't work in iPhone

Hi,

I have just got a second user Apple iPhone 12 Pro from my girlfriend and I am trying to set it up to work with my SIM, but it won't allow me to make calls or send messages using SMS.

I have tried to different SIMs from my existing phones, they work in my old Android phones but not in the iPhone.

The iPhone detects the SIM and the provider details, Tesco for one and O2 for the other.

If I go into Settings and About the Network Provider Lock option says No SIM restrictions, but under Physical SIM, Network it says Not available and Phone not allowed.

I have run all updates I can find on the iPhone, but I still can't get passed this.

Can anyone help at all please?

iPhone 12 Pro, iOS 26

Posted on Dec 8, 2025 4:40 AM

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Answer 1

Top-ranking reply

FelipeV

Level 6

12,053 points

Dec 8, 2025 5:37 AM in response to alamb200

Force restart the phone:

Force restart iPhone - Apple Support

If that does not solve the problem, the issue is most likely at the carrier end. They need to correctly provision the iPhone. If the customer service representative balks, ask them to escalate the problem with a supervisor.

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Answer 2

KiltedTim

Level 10

224,724 points

Dec 8, 2025 6:06 AM in response to alamb200

Phone not allowed makes me think it may be blacklisted.

Was the person you got it form using it successfully before you got it?

What carrier were they using it with?

Did they fail to pay off a balance due on the phone or terminate their cellular service without paying off a balance due to the carrier?

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Answer 3

LD150

Level 10

99,661 points

Dec 9, 2025 1:52 AM in response to alamb200

Try this

Change of SIM

1. Settings, Apps, Messages,

2. turn off iMessage

3. Settings, Apps, Facetime,

4. Turn off Facetime,

5. Power down the phone

6. Turn on the phone again

7. Settings, Apps, Messages, turn on iMessage,

8. Settings, Apps, Facetime, turn on Facetime

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Answer 4

alamb200 Author

Level 1

10 points

Dec 9, 2025 7:25 AM in response to LD150

I have just done a check on Check IMEI number / ESN - free checker IMEIpro.info and it has come back as clean.

Brand:Apple Apple IMEI checker is availablePhone model:iPhone 12 Pro A2407Blacklist status*:CLEAN

At least that is one less thing to have to think about.

I will try to speak to Tesco and see what happens.

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Answer 5

FelipeV

Level 6

12,053 points

Dec 8, 2025 5:20 AM in response to alamb200

You would probably need to get in touch with the carrier you want to use so they can provision your iPhone.

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Answer 6

alamb200 Author

Level 1

10 points

Dec 8, 2025 5:25 AM in response to FelipeV

I did speak to them first, but they couldn't see anything wrong.

I have tried using Sims from O2 and Tesco with the same result.

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Answer 7

alamb200 Author

Level 1

10 points

Dec 8, 2025 6:04 AM in response to FelipeV

I have reset the phone about 5 times so far, without any progress.

I did try the chat support, but they couldn't help, and told me to take it in to a store to look at.

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Answer 8

Dec 9, 2025 1:23 AM in response to alamb200

me to

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Answer 9

alamb200 Author

Level 1

10 points

Dec 9, 2025 12:54 AM in response to KiltedTim

I have asked my girlfriend and she doesn't know why it would have been blacklisted. How would I check?

If it has been, is there a way to get this unblocked? Sorry, I am used to Androids, this is my first experience of an iPhone.

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Answer 10

Dec 9, 2025 2:01 AM in response to alamb200

If a carrier has blacklisted a phone for being lost or stolen, I believe that they would only consider removing the blacklisting for the owner who reported the loss or theft, with proof of ownership.

If a carrier has blacklisted a phone for non-payment of a contract, they would likely require payment of the remaining balance of the contract. Should the phone be a used one and the balance be owed by the previous owner, they might not want to discuss the account for privacy reasons - in which case there might be no way to get the second-hand phone off of the blacklist.

Neither of these are “iPhone” things; they are things you might encounter just as easily with Android phones.

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Answer 11

LD150

Level 10

99,661 points

Dec 9, 2025 2:00 AM in response to FelipeV

FelipeV wrote:

You would probably need to get in touch with the carrier you want to use so they can provision your iPhone.

That doesn't apply in UK, as they mentioned Tesco that is where they are. Phones cannot be locked or prevented from activation since 2020 here

Unless if course it isn't from a UK girlfriend but is imported.

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