Jack Bauer is back, and that distintive ringtone at CTU got my attention. Google turned up this site
http://www.ccir.ed.ac.uk/~jad/ringtone.html
I downloaded the CTU24.wav file, and then had to convert it for my Polycom 501 deskphone:
sox CTU24.wav -r 8000 -U ctu_24.wav
I just had to put it in the phone’s boot directory on my Asterisk server and reboot the phone. Here’s the CTU24.wav ringtone for Polycom.