I did not find it in Twilio documentation that I can change it.
Does anyone has a solution to this problem?
Perhaps it is possible to replace the mp3 file that is downloaded to the browser and used as a ringtone.
I need this, because my clients are somewhat annoyed by the default ringtone of Twilio browser client.
It is possible to change default incoming ringtone with some workaround.
Following Twilio client API: https://www.twilio.com/docs/client/device#sounds you can disable incoming ringtone calling Twilio.Device.sounds.incoming(false). Then you will need to hookup to event Twilio.Device.incoming and manually start you ringtone and hookup to other events to stop playing music when call is answered/cancelled.