The person that does respond to Radley's call is neither Kalin nor Scotch. In fact, Cecil is not entirely certain it's Radley's call he's responding to in the first place.

"Hello? Is someone there? Are you alright? Wait, was that a spark?"

Despite the fact that his footsteps are approaching, that last comment is far more difficult than the rest to hear. Maybe he didn't mean to say it out loud in the first place.