1. Edit 'VoIP Provider' > 'General' tab.
2. Confirm 'External Number' and 'Authentication ID' are set to the main trunk ID (which they will be if the trunk registered).
3. Select 'Outbound Parameters' tab.
4. View the 'Content of SIP fields' section, and ensure the following SIP Fields have the associated variables set:
   1. From: User Part = "LineNumber". Alternatively, depending upon your configuration, set this to "AuthID".
   2. From: Display Name = "LineNumber" external number of line
   3. Remote Party ID - Calling Party : Display Name = "OutboundCallerID" Outbound caller Id taken from Extension settings in management console. Alternatively, depending upon your configuration, set this to "LineNumber".
   4. Remote Party ID - Calling Party : User Part = "OutboundCallerID" Outbound caller Id taken from Extension settings in management console. Alternatively, depending upon your configuration, set this to "LineNumber".
   5. Remote Party ID - Calling Party : Host Part = "GWHostPort" gateway/provider host/port
   6. Click 'Apply'.
5. Then under the extension in question, where spoofing is required, select the 'Other' tab.
6. Set 'Outbound Caller ID to the CLI you wish to spoof.
7. In certain cases you may also need to set they 'SIP ID' to the CLI you wish to spoof