My work phone died (screen shows white all the time) so I’m messing around with my old phones. I got out my old Nokia 6800a and put my work SIM in it, but it was locked. Google lead me to: http://www.peters1.dk/unlock/nokia/online.php?sprog=en which correctly gave me the unlock code #pw+317346746545441+7# and I happily unlocked my phone.

I get the impression this phone uses some seriously old tower technology because my speakers make a lot of noise when I send/receive text messages and calls. Might have to go back to another phone.