If the system is programmed so that calls come direct to your handset, not a ring group, you can do this easily by from your handset dial 751, push a key you want to program, 10, your voicemail pilot ID. And assuming the rest of the programming in the system is correct, and you have a voicemail setup on your extension, this will work.
Alternately, you can program the system to do as conxtel has advised, and create a mode to program a night mode.
12-07 - Set Name of Mode
22-02 - Set trunks to a mode for their type (DIL for PSTN/POTS, DID for SIP/BRI/PRI)
22-07 - Set Destination for your voicemail (virtual extension recommended, 11-03 to create, 24-09 to forward to voicemail pilot)
22-10 - Set tables for your DIDs for SIP/BRI/PRI
22-13 - Set Mode to Table as above per trunk group
22-11 - Go to table for your 'Night' mode, change Target 1 destination to your Voicemail (virtual extension recommended, 11-03 to create, 24-09 to forward to voicemail pilot)
Other points you may be interested in
47-02 - Make sure mailbox is setup
11-07 - Voicemail Pilot is normally your last Dept Group Pilot.