Hi Retell AI Support Team, I hope this message finds you well. I am currently implementing a workflow where I use the transfer_call function to hand off calls to an external phone number. This destination number connects to an IVR system that has strict security protocols. The Issue: Our receiving IVR system identifies and authenticates incoming calls based on the Source IP address. Currently, because the calls from Retell seem to come from dynamic IPs, our IVR cannot consistently verify that the call is originating from your platform. Could you please assist me with the following: Static IP: Is there a way to configure a dedicated/static outbound IP address for my account or for specific phone numbers so we can whitelist it on our firewall? IP Ranges: If a static IP is not possible, could you provide a documented list of all public IP ranges (CIDR blocks) used by Retell for outbound SIP/PSTN traffic? We need this to update our allowlist. Any documentation or technical details regarding how your outbound media/signaling traffic is routed would be greatly appreciated. Thank you for your help. Best regards,

Hello @nicogapa13 , IP block for traffic: 18.98.16.120/30 (All regions), 143.223.88.0/21 (United States only), 161.115.160.0/19 (United States only)