Freeze the exact order, handoff and failed attempt
Record UTC and local time, contracting and billing entity, service identifier, site, NBN service, ordered channels, number inventory, equipment boundary, PBX product and version, configuration owner, direction, called and calling numbers, expected route, first response, answer and audio result. Redact credentials while retaining field names and retrieval time.
Classify the first unexpected boundary: order, delivery, access, addressing, DNS, PBX object, outbound request, provider response, inbound attempt, route, channel admission, dialog or media. Do not import a proxy or credential from the adjacent BYO VoIP guide.
Establish the broadband and equipment boundary
The current CIS requires an active Aussie Broadband NBN plan and customer-supplied fixed voice system. Confirm NBN state, public-address behavior, route, DNS and the exact adapter, gateway, SBC or PBX demarcation in the order. A working Internet session does not prove that the voice handoff, SIP path or media path is accepted.
The CIS language about an Aussie Broadband adapter and its later statement that adapters are not mandatory must be resolved from the selected architecture, not guessed. Do not bypass a managed device or change a supplier-owned boundary without approval.
Prove the supplied SIP model before changing NAT or credentials
Compare the loaded PBX values with the current provider handoff: proxy or target, authentication identity, secret owner, source-address rule, registration requirement, transport, port and number format. Preserve the first request and response at an authorized observation point.
The general CGNAT article describes broadband address options but does not prove that this trunk requires a public static address or port forwarding. Determine whether the failure is missing traffic, rejected authentication, untrusted source, wrong object or wrong route before changing NAT, firewall, credentials or transport.
Trace number delivery and channel admission separately
For inbound failure, establish port or assignment state, provider attempt, delivered Request-URI or called-number header, PBX receipt and route match. For outbound failure, preserve the selected trunk, Request-URI, caller identity, Call-ID, response sequence and any provider restriction. Port acceptance, number inventory and one successful direction do not prove the other direction.
Compare ordered channels with PBX concurrency controls, simultaneous active dialogs and the precise rejected attempt. One channel is described as one simultaneous call, but channel entitlement is not bandwidth, call-start rate, PBX resource capacity or media quality.
Keep signaling, codec and media evidence distinct
After answer, preserve both SDP bodies, selected payload, DTMF method, packetization, RTP endpoints, packet directions and decoding for the same authorized attempt. A SIP response or connected timer does not establish two-way audio.
The reviewed public SIP-trunk sources do not publish a universal codec, fax, media-port, TLS or SRTP contract. Ask the provider for the selected service handoff instead of transferring values from BYO VoIP, an adapter guide or another provider.
Retest one correction and close with provider evidence
Apply one authorized correction and repeat the affected ordinary call plus an unaffected control. Preserve access state, SIP exchange, route match, answer, both media directions and hangup. If a port or supplier change is involved, keep the former service active until the provider confirms the approved cutover and the new path is verified.
Check public outage information only as timestamped context, then preserve the account-specific fault, provider observation, restoration notice and customer retest. Confirm IPND address, presented identity, callback, power, Internet dependency and an independent calling method through the approved emergency-readiness process; do not use 000 as an uncoordinated test. No trunk, port, call, media or emergency result was tested for this diagnostic.
Sources & applicability
Primary references for the technical details above. Operational examples and planning checklists are VoIP.info editorial guidance.
- Aussie Broadband — SIP Trunks ↗
- Aussie Broadband — SIP trunks Critical Information Summary, 1 July 2026 ↗
- Aussie Broadband — BYO VoIP settings, updated 14 September 2026 ↗
- Aussie Broadband — Integrated Public Number Database and emergency-service address, updated 26 August 2025 ↗
- Aussie Broadband — phone-number port timing, updated 5 May 2023 ↗
- Aussie Broadband — port forwarding and CGNAT, updated 13 August 2023 ↗
- Aussie Broadband — current, upcoming and past outages ↗
- Aussie Broadband — report a fault in MyAussie, updated 26 February 2024 ↗
- Aussie Broadband — business support and service-delivery contacts ↗
Examples require adaptation to your topology. No live PBX or hardware testing is claimed.