What is the destination for the Incoming Call Route? That single phone whose voicemail should cover all calls, or a hunt group such as Main? If it is that single phone, make sure you have the Voicemail box checked for that phone only.
If HG 200-Main, which has several extensions assigned to it so multiple phones ring, but you want Ext. 201's mailbox to answer the calls. You would create a short code, such as *601 / Voicemail Collect / "#"201 . Dial it, and confirm that mailbox 201 answers.
Now create a new user, lets say Ext. 601, name it Mailbox 201. Go to the Forwarding tab, check the boxes for Forward Unconditionally, forward Internal Calls, and Forward Hunt Group Calls. Dial 601 and confirm that mailbox 201 answers.
Create a new SEQUENTIAL hunt group, such as 699 and name it MBX 201. Put Ext. 601 in as the only member. Call 699 and confirm that mailbox 201 answers
Finally, on hunt group 200-Main, go to the Overflow tab, set the overflow time to how long calls should ring before covering to Mailbox 201, and put hunt group 699-MVX 201 in there as the selected overflow group. Set the No Answer Time on the Group tab to the same as the Overflow Time. UNCheck voicemail for 200-Main
Now call 200, the phones in the group should ring, and after a delay, mailbox 201 should answer.
AND, on 200-Main, you can set 699-Mbx 201 as the Night Service Destination, put a Set Hunt Group Night Service-200 button on a phone somewhere, and when you push it before leaving for the day, Mailbox 201 answers immediately, instead of after a delay
