I have not done this yet but is there any reason it won't work? If I connect a loud ringing device to pins 3&4 of the jack for a digital phone isn't that the same as connecting it to an analog extension?

LOL. That won't work. No ring voltage to a digital set. But give it a try, I have been wrong in the past.

The digital set requires a 2pair connection and if you want an analog you just use the single pair. Ports can be either analog or digital which is why I'm curious if it will work.