PortSIP PBX assigns default extension numbers to built-in system services.
These extension numbers are reserved and cannot be used when creating user extensions.
Default System Extensions
Call Announcement Service: 555
To change this number, go to Advanced Services > Automatic Callback.
Call Park Service: 666
To change this number, go to Advanced Services > Call Park > Global Settings.
Voicemail Service: 777
To change this number, go to Advanced > Voicemail.
Call Monitor Service: 888
To change this number, go to Contact Center > Monitor Service.
