iphonesimunlock
This must be some basic stuff but I'm unable to figure it out.
I've restarted my iPhone, inserted my security code and then when the numpad appeared to insert my SIM pin code, I pressed the home button and now I can't trigger that numpad again to insert my pin code.
The only thing I see is Locked SIM in the upper left corner and can't do anything about it.
The question: How can I trigger the panel to unlock my SIM card again?
No, you do not have to enter any sort of unlock code for any iPhone unlock event.
iTunes contacts the registration database when a phone is restored to determine the lock status and set the appropriate carrier settings file if needed.
So, in your case one of two things has happened.
The unlock happens when you restore your device - either as an over the air (OTA) activation or tethered to iTunes.
The carrier should be able to query the live database to see if your IMEI is unlocked or you could try getting another cheap SIM (or borrowing a friend's SIM) and just testing the phone yourself. If you restore the phone twice after it gets unlocks, you will not see this message - but you should get it when it's first unlocked.
This means that the phone was software unlocked (which requires a jailbreak). Because you updated the device using iTunes, you have removed the jailbreak and the phone is no longer in a state of carrier unlock. This is actually common practice and a great number of people end up getting burned (they either just don't know better or are lied to and told the phone is factory unlocked).
You can call the carrier the phone is originally locked to and have them unlocked it (they may charge a modest fee or if you luck out, do it for free as that particular model no longer being manufactured) or re-jailbreak the device and software unlock it yourself, provided you have a baseband revision of 06.15.00 or older.
Note: Apple can't help in these matters.
Best Answer
On iOS 10, go to Settings > Phone > SIM PIN to unlock your SIM.