As mentioned, that is what paging pro can do.
You can also jsut cron a call.
0 10 * * 1-5 /usr/sbin/asterisk -rx "channel originate local/5197@from-internal application playback en/custom/buzzer-1_GJ9hRbVu"
10 10 * * 1-5 /usr/sbin/asterisk -rx "channel originate local/5197@from-internal application playback en/custom/buzzer-1_GJ9hRbVu"
0 12 * * 1-5 /usr/sbin/asterisk -rx "channel originate local/5197@from-internal application playback en/custom/buzzer-1_GJ9hRbVu"
30 12 * * 1-5 /usr/sbin/asterisk -rx "channel originate local/5197@from-internal application playback en/custom/buzzer-1_GJ9hRbVu"
20 14 * * 1-5 /usr/sbin/asterisk -rx "channel originate local/5197@from-internal application playback en/custom/buzzer-1_GJ9hRbVu"
30 14 * * 1-5 /usr/sbin/asterisk -rx "channel originate local/5197@from-internal application playback en/custom/buzzer-1_GJ9hRbVu"