Hello Vapi Team, After extensive debugging with our carrier, Sipgate.de, we have isolated the exact cause for the 403 Forbidden error on all outbound calls. The problem is that your server is sending the wrong value in the From header of the SIP INVITE request. Here is the exact error response we received from Sipgate's servers during a call attempt: SIP/2.0 403 Username in From Field required As you can see, your server is sending the E.164 number in the From header: From: sip:+4920185896856@sipconnect.sipgate.de Sipgate requires the SIP Username in this field for authorization. The correct header should be: From: sip:3690966t0@sipconnect.sipgate.de This is a SIP header formatting issue on your backend. Please have your engineering team correct the behavior for your BYOC Sipgate integration. Organization ID: 15889908-dd32-4ce8-a845-4b228e4ed769 Phone Number ID: 009dec31-7f73-42b0-9f55-b17e6414da1b Thank you. #1211483291191083018

Thank you for flagging this issue with our SIP infrastructure. We are currently in the process of updating it to better fit SIP communication standards, but this will take a considerable amount of time to deploy this. Thank you for your patience in the matter

can you fix the bug please?

Our team is working on this request, and it will take some time since it requires significant changes to our infrastructure. While we are working on it, could you please try using the SIP registration in your SIP trunk? This may allow you to use your username for outbound authentication plan for SIP invite

from:

headers. https://cdn.discordapp.com/attachments/1404899412626640916/1407132741425954847/image_6.png?ex=68a4fdfc&is=68a3ac7c&hm=a6ae0ad6fff69206ea8dd8c0e12ae054dab9c29e48c2023f1bd7c97cfee6c0cb&

i tried it. It doesnt work.

We will check with the team for an update regarding the SIP Infrastructure change.