All my Nokia phones still work or should work,
(Nokia 5110 from 1999, Nokia 5125 from 2001, Nokia 1100 from 2004, Nokia 5200 from 2007, Nokia N86 from 2009).
My carrier had to convince me to leave my 5125 as they were turning off the analog service (it's now used as an alarm clock), and I still use the 1100 sometimes.
However, I finally switched (partways) to Samsung, entirely due to the software (I wanted an Android phone), even though my N86 is better built and has a better camera (and hardware camera button, which I prefer).