Sprint s7 SM-G930P boost mobile compatibility issue

[Kendogg28]

Is there a reason why my sprint s7 (SM-G930P) wouldnt be compatible with boost mobile? I bought the s7 used but with the sellers help we had sprint unlock the network lock. But when the sim cards in it says carrier is at&t. And now, boost mobile tech support is telling me its not compatible. But its a sprint phone. About info says brand is sprint. Phone has sprint apps and sprint logo when starting up. Was used by original owner on sprint network/ phone plan. Talked to sprint tech support myself too have it unlocked (network lock). I had called boost tech support to check if i could hook it up before i bought it and gave imei number and was told yes. Now im 100 bucks to the wind which usually wouldnt be a big deal except i was laid off several days earlier. And now tech support constantly hangs up on me and wont put me through to supervisors. If someone could help me id greatly appreciate it