There was an existing RJ11 socket in the wall behind my bed. Sadly, nothing more exciting.

It's totally possible it was a hiccup. I had been using the line for weeks with the same number, and then it suddenly started to reliably redirect to emergency dispatch.

I thought I had read previously that numbers containing 911 would redirect in the case that a potential victim has misdialed in a hurry. This incident was over a decade ago, so its possible that I misread an article or found a garbage source.