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Convert Nokia 6200 (NPL-3) to 6610 (NHL-4)
Manual:

Find and replace all SAW filter and antenna switch from 6200 marked in red with filters from 6610.

Add the blue marked chip (TRX2 BFMON505) to 6200 from 6610

Upload the special PM file for 6200 to avoid speaker and microphone troubles.

Reset phone to factory defaults and unlock if nessecary!