Star Code/Feature Code List (Grandstream)
Star Code/Feature Code List

*20 - Call Forwarding (Include Destination Number)
Example: *205551113333
*21 - Disable Call Forwarding
*22 - Do Not Disturb - Send to Busy
*23 - Do Not Disturb - Send to Voicemail
*24 - Disable Do Not Disturb
*25 - Set Failover Number (Include Destination Number)
Example: *255551113333
*26 - Set Failover to Voicemail
*27 - Blacklist Last Caller
*67 - Block Caller ID (For Next Call Only)
*30 - Block Caller ID (For All Calls)
*68 - Unblock Caller ID (For One Call)
*69 - Call Return
*31 - Unblock Caller ID (For All Calls)

123 - Access Voicemail