Loopback SIP Trunk returns 403 Forbidden in 3CX V20

[MAGTEL SYSTEMS]

Hi,


I'm trying to use a Loopback SIP Trunk to send calls to a Call Processing Script (CFD) in 3CX V20.
My setup is:

• 3CX V20 on Debian 12
• Outbound rule: Prefix 9 → Loopback SIP Trunk
• Loopback trunk default route → Call Processing Script (dncr_check)

When I dial:I get the following error:
403 Forbidden
Call to 90507493001@(Ln.10002@loop_back) has failed

 

[Charles_3CX]

Why is a loopback required here, please? Can you not just route directly to the Script?




Or assign the script to check calls when they arrive on the trunk?

 

[MAGTEL SYSTEMS]

we have to run the script on outgoing call . not for the incoming call

 

[Charles_3CX]

The scripts are designed for incoming calls. We don't have any information on outgoing calls, or whether this is an error or not; I'm afraid.