### Instruction: What should you do when your rock climbing partner calls out "On Belay?"
### Response: 1. Check that their harness is properly buckled at the waist and doubled back.
2. Ensure the leg straps are properly bucked and doubled back. Check that the leg loops are not twisted.
3. Ensure a figure eight knot is tied at the end of the climbing rope, extending through both loops in the harness and has a fisherman's knot as a backup.
4. Check that your own harness is properly buckled around the waist, legs and that leg straps are not twisted.
5. Ensure the climbing rope is in your belay device, that a locking carabiner goes through both the belay device (and rope if an ATC device) and your belay loop on your harness. Ensure the carabiner is locked.
6. Ensure that you and your partner are on the same rope. Your partner should be on the side of the rope closest to the climbing wall.
7. After all safety checks are completed, then call out "On Belay!"