Final answer:
The message is likely related to the network lock feature. Contact your carrier for an unlock code or consider using a service to unlock your phone.
Step-by-step explanation:
The message you are seeing on your iPhone 7 after inserting your SIM card from your Samsung is likely related to the network lock feature. Some phones are locked to a specific carrier, and if you insert a SIM card from a different carrier, the phone may display a message asking for an unlock code.
To resolve this issue, you can contact the carrier that your Samsung phone was locked to and request an unlock code. Once you have the unlock code, you can enter it on your iPhone 7 to remove the network lock.
If you are unable to obtain the unlock code, you can also consider using a service or software to unlock your phone. However, it's important to note that unlocking your phone may void warranty and could have legal implications in some countries.