That sounds frustrating especially if it’s blocking your integration. I’ve debugged several SIP trunk auth issues (including 403s caused by nonce mismatch, realm inconsistencies, or header formatting quirks). Even when credentials are correct, it’s often a subtle digest validation issue. If you’d like, share a redacted SIP INVITE + 401/403 exchange and I can help pinpoint what’s failing while you wait for forum access.. @SteveGray