MY HUSBAND WAS ABLE TO FIND A SIMCARD AT A LOCAL STORE, I WAS ABLE TO ACTIVATE MY PHONE AFTER A FEW ATTEMPTS.
GOOD LUCK! (I BOUGHT THE S9+ / UNLOCKED FROM SAMSUNG)
Sorry to hear that, @Nessa246. Let’s check this thing out. To further research, we'll need to access your account. Please, send us a private message with your phone number, PIN, IMEI and ICCID (SIM card numbers).
To send a private message just click on the picture of any Boost Mobile agent and, in the next screen, click "send this user a private message".
This will work ! I just activated my samsung unlocked galaxy s9 plus midnight black phone on boost mobile. I bought this phone with the deal that they had at samsung's website and bought the exact same SIM card as mentioned, SIMOLW506TQ, which they should have at your typical Best Buy or Amazon, or Boost mobile store. I just swapped my galaxy s6 for the galaxy s9 plus. Hope this helps !