I need to effectively have 3 "main" numbers as I will have a number of work from home users and need what would be 3 "regional" local area code numbers all ringing to the same auto-attendant. Is it possible?
Chris is correct if you are wanting callers to hear a greeting and make a selection. However, instead of a custom rule, you can assign those 'main' numbers directly to the IVRs and still have them available for outbound caller ID. My mantra has always been the less programming the better.
If you are NOT wanting a greeting however, custom rules are required to route the calls directly to 3 virtual extensions (add a user without a phone or phone number) and assign the agent/s to the call handling for each one. Do not assign the 'main' numbers directly to keep them available to anyone who would need to use them for outbound caller ID. And you can turn off the voicemail or have any messages delivered directly to the agent's mailbox using the message recipient option or via email as an attachment through the notifications advanced settings.