iphone 4 invalid sim, how to fix it?

Try following this article:

http://support.apple.com/kb/TS4148

What did your carrier say when you contacted them about your invalid sim?

Are you using a supported carrier http://support.apple.com/kb/ht1937

you have got right answer ?

i have also same problem

I am so happy that I finally fix this invalid sim card with iphone4.

What I have:

- iphone 4

- iphone 6

- sim card 1 (invalid for iphone 4, but works on iphone 6. This card's original carrier is from a foreign country)

- sim card 2 (works for both iphone 4 and iphone 6)

What I did:

- put sim card 2 into iphone 4

- Settings -> Cellular -> Cellular Data Network

- Because sim card 2 works for both iphones, then you could see that it has carrier settings like "gprs.carriernameXXX.ch" (e.g. gprs.swisscom.ch)

- Then, keep your iphone4 staying in this setting page

- Remove sim card 2

- Insert sim card 1

- Then you will see the left-upper-corner of iphone 4 is searching for carrier

- Wait and patient, then it works for me. iPhone 4 found the same carrier as "gprs.swisscom.ch" for sim card 2.

- After two minutes, iPhone 4 reminds me to have an update of carrier, i click ok.

I did this, because i noticed that when i insert sim card 1 into iPhone 4, it shows "Carrier not available" in General->About-> Carrier: Not available

Then it reminds me that, maybe I could insert a working sim card to record this Carrier setting.

Because I want my sim card 1 (foreign sim card) working by using the same carrier as sim card 2.

Hope it helps you.

Cheers,

Lulu

Problem solved! Thank you so much. I was stuck in one country trying to use my sim. This was a lifesaver.

I "heart" lovelulu LOL