‘Spoofing’ – or caller line ID / outbound number presentation – is the practice of causing a telephone network to indicate to the receiver of a call that the originator of the call is number other than the true / real originating number, or main trunk number (SIP ID).  Spoofing is often used as a temporary measure whilst numbers are ported in order to present as the outbound CLI a business’ main number – although it can be used permanently in cases where a number cannot be ported in.  There are two steps to setting up spoofing / number presentation.

Note: if you are attempting to present a purchased (provisioned) or ported number, you do not need to set up a spoofed number as detailed in Step 1 below.  Please also note for the sake of brevity in this article, number presentation can be assumed whenever spoofing is referred to.

Step 1: Set Up The Spoofed Number on the SIP Trunk Plus Portal


a) Set up a spoofed number on the SIP Trunk Plus portal as described in this solution.


Step 2: Configure the PBX to Correctly Present the Spoofed Number

 

a) Configure your PBX such that the ‘From’ number / address must be the main trunk ID number / DDI, with the spoofed DDI/CLI being set in the RPID (Remote Party ID) field (although of course the RPID may also be the main trunk ID number / DDI if spoofing is not required). The important point to note is that the 'From' number must always be the main trunk ID number / DDI, regardless of whether spoofing is required or not.


b) Ensure the correct settings are correctly configured in your PBX according to your manufacturer guide to present remote party ID.  In 3CX, for example, via the management console:


  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:
    a. From: User Part = "LineNumber". 
Alternatively, depending upon your configuration, set this to "AuthID".
    b. From: Display Name = "LineNumber" external number of line
    c. 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".
    d. 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".
    e, Remote Party ID - Calling Party : Host Part = "GWHostPort" gateway/provider host/port
    f. 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
  8. Click 'Apply'.


Setting up the portal and your PBX in the way described above will remove any ‘Forbidden’ calls when attempting to spoof an outbound CLI.


In addition, the 'Barred Calls Log' gives detailed reason for a call that has been barred and is an excellent first for to call for troubleshooting.  For a list of error codes / reasons please refer to Barred Calls Error Codes.