PIN2: secrets of use?

Question

SIM cards

Any SIM card has two pin codes: PIN and PIN2
If everything is clear with the first, then the second is something completely useless.
Question: Has anyone ever actually used the PIN2 feature for "peaceful" purposes? If yes, then in conjunction with which devices they were able to use them (especially interested in the connection with USB whistles).

Answer 1

A common classic use of PIN2 is to limit the ability to dial numbers with masks.
Let's say I have an MTS-Ukraine number with free calls within the network and it is not used for calls to other networks.
I don't want to mistakenly call another operator.
My operator codes are 50,66,95,99. Country code +380
Create dial masks +38050,+38066,+38095,+38099 and *1 for USSD requests.
Now I can easily call my operator without the risk of accidentally dialing the wrong number or calling the wrong SIM.
The number of masks is limited (usually 6-10) and depends on the specific SIM card. It may differ even on different SIM cards of the same operator.
The restriction applies to both calls and sms.

Answer 2

In short, PIN2 is an additional user blocker for the use of SIM Card and Moble Phone.
Used on some phones, for various blocking:
- blocking outgoing calls from the phone's address book and special numbers (112 and others) (used on Nokia)
- children's mode, when any call from the device occurs to a number entered in the menu in advance (not compatible with the previous paragraph)
- blocking some settings of the telephone set
Protection for short numbers should be on the part of the operator:
- in a megaphone like this
- I don’t know the rest