hey @Vapi @Vapi Support Bot @User We are dialing a Free Vapi SIP URI: sip:cloudtalk-tax-ai-2@sip.vapi.ai According to your SIP introduction docs, Free Vapi SIP should require no authentication or SIP registration. However, our SIP trace shows Vapi responding to the INVITE with: 401 Unauthorized WWW-Authenticate: Digest realm="sip.vapi.ai" Our Asterisk endpoint has no outbound_auth configured because the Free SIP docs say no auth is required. CloudTalk registration is successful, and our SDP now advertises a public IP, so CloudTalk/NAT are not the blocker. Please confirm whether Free Vapi SIP currently requires digest auth in practice, or fix the SIP URI so it accepts unauthenticated INVITEs as documented.