First, build your attendant menu(s) and then build the schedule. By default each account has one auto attendant scheudule. Additional attendant schedules are add-on services with a monthly fee and can be purchased by submitting a request via Aptela's online ticket portal.
For instructions to build your Menus, click here. Menus, also referred to as "Call Trees", greet callers and provide callers with options to choose to reach their desired destination. A menu might sound like this, "Thank you for calling ABC Company. Press 1 to dial by extension, Press 2 to dial by name, Press 3 for Sales, Press 4 for Customer Service." Many companies will build multiple menus to address greeting callers during business hours, after hours, on holidays, etc. Go to the article "Building Auto Attendant Menus" for instruction.
Once your menus are built, you will create the schedule. The schedule is found under the "Auto Attendant" tab. The schedule assigns the menus to play based on time of day and day of week.

