Download a desired MP3 music file and copy it onto a USB memory stick (pen drive). You have to make a folder called “mp3” and put the file in that folder.
Insert the USB memory stick into your Cisco SPA-525 phone
Press the Menu Button (looks like a File Folder)
Option 6 user Preference Press Select
Option 2 Audio Preferences Press Select
Use the right arrow on the Line you want to change the ringer for (line 1 is default)
Now use the down arrow to go to the bottom of the List and you will see Ringer 12 and 13. You are allowed to have two custom Ringers on the Phone.
Click the FromUSB button
Then select which one of the two custom slots you want to save the mp3 to. (does not matter which)
Your Ringtone is now set.