I have an Alcatel One Touch Idol 3. Occasionally, instead of ringing like it should (using the ringtone I selected as...

Just go to settings, and select “Accessibility” You’ll see a choice for vision. Select vision, then turn off “Inversion.” That should fix it for you. (Note: this is how it works on my LG phone. I imagine it should work in a similar fashion for your phone, too.)

I already checked that. The ringtone was set to default.