### Answer This error is coming from your telephony provider (likely Twilio) and indicates that the phone number you're trying to use as the caller ID hasn't been verified in your Twilio account. [(1) ]() ## For Twilio Users You need to add and verify the number as a Caller ID in Twilio: 1. Go to the [Verified Caller IDs page]() in Twilio Console 2. Click Add a new Caller ID 3. Enter the phone number you want to verify and select a verification method 4. Enter the OTP code you receive to complete verification Once verified, you can configure SIP Header Rules to display that caller ID: 1. Navigate to Elastic SIP Trunking → Trunks → [your trunk] → Termination 2. Scroll to Header Manipulation and open View all SIP header manipulation policies 3. Create a policy with a request rule setting: - **SIP header field**: From number - **Action**: Replace with - **Value**: Your caller ID in E.164 format (e.g., +18881230987) 4. Apply the policy to your trunk's Termination settings ## For Telnyx Users Verify your personal number in Telnyx (non-Telnyx numbers must be verified) , then set it as a Caller ID override in your SIP Connection's outbound settings. [(2) ]()

​ To learn more, see the sources I considered: [[1] Twilio](https://docs.retellai.com/deploy/twilio) [[2] Using Telnyx Verified Number as Caller ID on Outbound Calls by Voice Agent](https://discord.com/channels/1186424376300679209/1400660575100604537) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.