The difference between the two things already having been answered:

As long as the "Bell" is ringing or calling an extension of some sort, I could see if the ANow sotware doesn't have the capability, you could rig it up pretty easy. Asterisk can generate calls by placing a file into a directory on the system with the call details, so you'd merely need cron jobs or some other scheduler to do that, and it would "dial" your SIP speakers or something and drop it into a call context where it plays the sound file out.

It offers an incredible tool box, but with a bit of a learning curve.