We are reporting a deterministic inbound Custom Telephony issue. Summary: - Australian geographic number (+61) imported and bound to inbound_agent_id - Inbound SIP INVITEs reach Retell and are immediately rejected with SIP 486 USER_BUSY - Call duration ~1–2 seconds - Behavior is deterministic and number-specific (AU only) Control test: - Same PBX, same SIP trunk, same Retell agent - Spanish numbers work perfectly - Swapping only the phone number reproduces / resolves the issue instantly What has been verified: - Carrier and PBX routing confirmed - Number import and inbound_agent_id binding confirmed - No concurrency, saturation, or rate limiting - SIP 486 is generated by Retell Relevant precedent: https://community.retellai.com/t/reset-the-inbound-sip-routing/411 This appears consistent with a cached inbound SIP routing / fallback state or internal validation issue. Request: Please check and reset inbound SIP routing / fallback state for this AU number. We can provide: - Org ID - Phone number - Exact timestamps - Full SIP traces

Hi @Laia you can provide details at support@retellai.com or you can dm so I can pass this issue to the team

Hi Shehroze, thanks for the guidance. I’ve just sent a detailed email to support@retellai.com with all the required information (Org ID, AU phone number, UTC timestamp, and issue summary) requesting an inbound SIP routing reset. Please let me know if you need anything else from my side. Thanks!