Voicent AutoRemdiner Enterprise version will meet your requirement. You
can setup AutoReminder system on one computer and all three office can
access to the appointment information.

You can look at the product information, feature comparison, online
demo and pricing at http://voicent.com/appointment-reminder-phone.php

Also feel free to download and test the software before you buy
at http://www.voicent.com/download. There is no expiration date
on trial.

> interested in learning more about the appointment reminder application, cost
> etc. We have three offices, but only one manages the schedules for all
> three.
>
>