LS990 - quick question on going zv4 to zv8

What I've got
A rooted LS990 on ZV4 (done on Octopus box from a repair shop) stock, official sprint rom. I get 'restricted access changed' notification, sometimes 'hands free activation message' and on mobile data I see 'GSM' icon circling even though I have a 3G SIM in it. The phone doesn't have TWRP but I see SuperSU installed. I don't know if the bootloader is locked or unlocked.

What I'd like to have
bone-stock 5.0.1 official sprint rom on ZV8. and the ability to use this SIM I'm currently using.

Suggestions/recommendation needed on how to go about it. I don't see any OTA on the phone. I just need confirmation from you guys. If possible, please point me to the exact posts.

Lg g3 ls990 Call recording Recording Problem

I have tried multiple call recording apps, like boldbeast, total recall, hd record, acr, automatic call recorder, but am facing voice distortion problem in both incoming and outgoing calls from other end .. it records but when i playback the other persons voice is not clear..
Please help !!!