Good day @Oswaldo. Thank you for contacting us! Did you purchase the device unlocked from Samsung? Are you using a brand new SIM card? We'll wait for your response.
The device is factory unlocked, and I'm using my old Boost mobile sim card though I haven't switch the sim card to the new phone.
You cannot use a SIM card that is already attached to another device. You'll need to purchase a new SIM card. But, first lets confirm if the device is compatible with our service. Would you please send us a private message? @Oswaldo
Note: For you to send a me a Private Message only need to click on my username, which will take to my profile, once you're there on the right side of the screen you will see the option to send me a Message.