[o]

[..]
  1. on_answer
  2. on_anything
  3. on_channel_found
  4. on_dchan_down
  5. on_dchan_up
  6. on_facility
  7. on_hangup
  8. on_info
  9. on_io_fail
  10. on_proceeding
  11. on_progress
  12. on_restart
  13. on_ring
  14. on_ringing
[..]