I recently got my mother's old Galaxy S6, and, after transferring all the texts and files over, tried to swap the SIM cards. Turns out the one from my Galaxy Grand Prime was too big, but after researching I found that I could carefully trim it down to fit. I did, making sure to not touch the chip itself. I pop it in, it fits perfectly, and the S6 tells me "The SIM card has locked", with the notification in the drop-down saying "Invalid SIM card".
Both phones were under Sprint, and the SIM card was trimmed correctly. Is it just a matter of Sprint "unlocking" it?
Good morning @CoolDakota. Do you have Sprint service or do you use a different carrier? In order for you to use the phone, on Sprint or on a different carrier, the phone would either need to be swapped (if on Sprint) or unlocked.
Alright. Sounds like you have active services with us, you need to purchase a different SIM card and then swap the Galaxy Grand Prime to the S6. The other SIM card is tied to the Grand Prime so you can't activate the S6 with that SIM card.