Nokia RM-77 how do i unlock a phone

I have this old phone and unfortunately my phone has died. how can i unlock this phone so i can use it with a different provider, i've heard people can do such a thing

i have a nokia rm-77
model: 6101b
IC: 661U-RM77
FCC IDPIRM-77
IMEI: 356642/00/130559/7
code: 0525914IM08R4

if someone could point me in the right direction that would be great

thank you!

 

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