TL;DW
LINDDUN card deck PDF for reference: https://downloads.linddun.org/linddun-go/default/v240118/go.pdf
How? Literally uses the same phone lines that have always been not secure or private
No google, samsung, or apple services in the background or separate carrier operating system. Plus the audio is always worse on the old phones. Unless law enforcement is out to get ya, the only thing being tracked is what time and number called you, or whom you called and at what time.