Phoenix Connectors are not a specific style of connector, but rather Phoenix Contact manufactures a broad assortment of PCB terminal blocks that can retain bare or ferruled wires by screw, bolt, spring, etc.
For the quick connect spring models the wires are secured simply by pushing in the wire, and are released with either an external lever (usually orange) or a recessed touch-proof release lever, as your particular connector seems to be. Although they manufacture a specific release tool, usually any suitably sized small screwdriver can be used to release the wires.
It appears that the holes on the short angled side might be the recessed release levers.
Steve