1. to set diverts to external numbers you need to program the speed dial 139 with the phone number then set the CF-EXT by dialing #670 to activate and #760 to cancel. This is done on each extn. SPD 139 is the last personal bin location.

2. Point a line at the voicemail ports and then dial this number to be answered by the voicemail. Then on answer dial * and the mailbox number followed by your mailbox password to access each mailbox to play/forward any messages.

3. If the voicemail has auto scheduling enabled in each mailbox this can be acheived, otherwise the user can activate/de-activate manually from he handset.

4. Not sure how it works in the US possibly done by extension billing in LCR

You will need a 20 key handset plugged into port 005 for system programming. You will need to consult the programming manual.

Day/night service on the DK424 is done manually.
The CIX system gave you an automatic day/night.
The upgrade from DK424 to CIX is not too hard so might be work investigating.

Regards
Carl