Star Trek sounds - Easily the best collection I've seen

Enjoy!!

http://www.trekcore.com/audio/

Converting MP3's for Polycom phones like the IP550

UPDATED:  An online tool can do this easily!  http://audio.online-convert.com/convert-to-wav  
Choose 16-bit resolution, 8000 Hz sampling rate, and Mono audio channels... and voila!  

After some research, I finally figured this out.  I think some other posts online are missing a step.

I'm on a Mac doing this... OSX 10.7.3 Lion

So, download Audacity:  http://audacity.sourceforge.net/

Install it.  Run it.

File> Open> feed it your MP3 or whatnot.

Under the Tracks menu, choose Stereo track to Mono.

Now, in the lower left corner of the main window, you'll see Project Rate (Hz), and it'll probably default to 48000.  This has to be changed to 8000 !!

File>Export> choose Format: Other Uncompressed Files
Then hit the Options button to the right.

Header:  Choose WAV (Microsoft)
Encoding:  Choose A-law or U-law.  Both worked for me and had little difference on the test file.

Now use your browser (Chrome in my case) to browse to the IP of the phone.  The default password for admin is 8679 (need to verify this again...)

Under the Preferences menu, choose Ringtones, and click the green '+' symbol to upload.

That's it!!