Hi there. I saw your message to HELPeR. I'll be sending you a response so we can get a bit more info and take a look into your unlock request.
I am having the same issue with my Galaxy s8+. I tried all the way back in October to get it unlocked and since then, Sprint says it is unlocked but I still receive error 407 whenever I try the UICC unlock
Let's go over the account and MEID of the device. My name is Juan and I'm with the Sprint social care department. Please send us a private message with your name, account holders name, phone number, account PIN or answer to the security question.
the last time you posted in here you were working on it with one of the agents via pm...what were the results from that and what were you told?
its a Boost phone? if so you will need to contact them in order to get it unlocked.