How could a landline be re-routed?

[seeker <mothman20052002@xxxxxxxxx>]

this happened to me.. i kept getting calls from one phone number
always at times i was not home. i kept trying it for months until one
day i tried it from work. then someone answered it and i heard sounds
from the building i was working in! i ran down to where it was and saw
an abandoned phone off the hook. someone said an off-premise extension
might have been used. It seems as if someone was routing calls through
a third party or being intercepted at my house, as many friends,
including those with ties to law enforcement, commented on my phone
being tapped.

another time i had a lucent digital answering machine that was powered
OFF and the phone rang several times. The machine turned ON and an
intercom feature in the unit was activated.

i have never had criminal issues so i feel my phone line was violated
and wonder what may have happened.