Hey! This is a common SIP formatting issue with some providers like BR DID. Even if “Enable leading plus for outbound calls” is disabled, Vapi might still use E.164 (+ format) if the callerId or from field in the API isn’t explicitly passed in the right format. Here’s what to try: In your outbound API call (e.g., /calls), explicitly set: "callerId": "3531972253" — without the +. Double-check your Vapi phone number settings → make sure “Allow non-E164” is enabled (you’ve done this ✅). If you're using a SIP header override field like customHeaders, you might try adding: "P-Asserted-Identity": "sip:3531972253@yourdomain" Also, check with Vapi support if they cache any formatting or have override rules on the SIP trunk config itself.