I was in a situation with buying an unlocked iPhone XR at Apple and trying to connect it to Boost, so Im posting this to help others who want to upgrade to the new iPhone but can’t because it’s sold out on the Boost website!!! The first thing I did was buy the unlocked version of the iPhone XR at Apple. I then called boost customer service and ordered the SIM needed to connect your boost data to the iPhone XR.
The SIM was free but you do have to wait about 2 days for it to arrive in the mail. When you call for the SIM make sure that the one they send has the SIM number (SIMGLW416TQ). Once you receive that SIM card you can either call boost customer service so that you can set up the SIM to your phone to get your data on it or you can go to the closest boost store in your area and they can set it up for you there.
Keep in mind though if you have it set up at the store they charge a fee. The price may very depending on where you are located, I paid about $30. It was totally worth it though I now have a new phone with my boost data and I love it!!!