Hello, Organization ID e5f689a3-55cf-470e-ae86-e6366aa65395 I’m setting up a BYO SIP Trunk in Vapi. I received all SIP trunk credentials from my provider and successfully added them to Vapi. However, Vapi is also asking for a phone number in the “BYO SIP Trunk Number” field. The issue is that my SIP provider did not give me a specific phone number. They handle outbound number rotation on their side and send dynamic Caller ID automatically. Could you please clarify: Is the phone number field mandatory? If yes, what should I enter there if my provider manages Caller ID rotation? Will Vapi force the number entered there, or can it pass dynamic Caller ID from SIP headers (From / P-Asserted-Identity)? My goal is to use one SIP trunk in Vapi while the provider controls number rotation externally. Thank you 🙏 https://cdn.discordapp.com/attachments/1472318078174892249/1472318078686859465/Screenshot_2026-02-14_at_21.34.54.png?ex=69922290&is=6990d110&hm=59701ec8c26d8782ee4d798aae3037fc769b6a27ac17dda22a159d09fb1568a5& https://cdn.discordapp.com/attachments/1472318078174892249/1472318079630311485/Screenshot_2026-02-14_at_21.35.25.png?ex=69922290&is=6990d110&hm=4f82bd9d1c41d8cd6aa1636bb55ce57b280becd7af08c480d2fa619813a49b22&

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Any updates?

Hi @vagaz, Could you provide me how the outbound call (Calls going out of Vapi) is sent? If you are given a user_id instead of a phone number, you can keep that user_id in the "phone number" field. Make sure to check the "Allow non-E164 phone numbers". This will accept the user_id as the number.