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1. Check the boundary before connecting a carrier
You can learn the browser course without a public carrier. The internal practice-call lesson is an acceptance exercise: its preflight, actual audio observation, disposition and matching report row determine whether your run passed. Reading the lesson or seeing a saved campaign is not proof of a completed call.
This page prepares a carrier handoff. It identifies the local signaling transport, listener and network path; it does not create a trunk, open a firewall or establish public telephone reachability.
You should seeContinue with read-only observations on the intended lab host. If you have not completed the course prerequisites, return to the preflight instead of assuming an internal call already worked.
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2. Record the three different addresses and paths
The local bind address/port belongs to the running SIP process. The public address/NAT mapping belongs to the network path. The provider hostname/port and authentication requirements belong to the carrier route. A value from one layer does not fill in the other two.
Signaling establishes and controls the session; media carries audio. A listener or SIP response does not establish two-way audio. Keep these observations separate in the handoff.
You should seeEach required value has a source. Unknown public mapping or provider requirements remains an unresolved prerequisite.
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3. Inspect the actual PJSIP transport
Run this on the Asterisk host for the intended lab. The command reads the running PJSIP configuration. Identify the transport name, protocol and local bind address/port relevant to the proposed route.
If the installation uses another channel driver, do not reinterpret its output as PJSIP evidence. Ask the owner to identify the driver and use the corresponding installed recipe.
- Before you use it
- Use an authorized shell on the actual lab Asterisk host. This reads configuration and makes no call.
asterisk -rx 'pjsip show transports'Captured demo response · 2026-09-23 21:35 UTC. Any filtering, hidden values or test-only data are identified in the capture label. Select Replay transcript to read the recorded output.
- Success looks like
- The retained lab capture shows transport-udp bound to 0.0.0.0:5061 and also lists transport-wss. Those are dated lab observations, not defaults to copy. Record your own relevant transport and bind.
- Stop if
- No such command or no transports: confirm PJSIP is the installed/loaded driver with the owner. Permission failure: obtain inspection access. An unexpected bind needs investigation before proceeding.
You should seeYou have a transport/protocol/local-bind tuple from your intended host. It still says nothing about public reachability, registration or audio.
04 / 06
4. Cross-check the socket at the operating system
The retained command checks UDP sockets and filters to the Asterisk process. It requires permission to see process names. Empty filtered output may mean missing visibility, a different protocol or a missing listener; it is not automatically proof that the service is stopped.
For a TCP/TLS/WSS route, have the owner inspect TCP listeners as well. This UDP-only example cannot verify those sockets. Preserve the selected protocol in the handoff.
- Before you use it
- Use the same host and a shell authorized to see socket/process information. This exact sample inspects UDP only.
ss -lnup | grep asteriskCaptured demo response · 2026-09-23 21:35 UTC. Any filtering, hidden values or test-only data are identified in the capture label. Select Replay transcript to read the recorded output.
- Success looks like
- Match the intended UDP bind from PJSIP to its socket. The retained lab has more than one Asterisk UDP listener; do not mistake another driver’s port for the selected PJSIP transport.
- Stop if
- If there is no match, check permissions and protocol first, then inspect the actual bind with the owner. Stop before writing firewall rules if the two observations disagree.
You should seeThe selected local UDP transport and socket agree, or a specific visibility/protocol/bind discrepancy is recorded. External firewall and NAT reachability are still untested.
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5. Identify the local route and ask for the public mapping
Read the local interfaces and routing table. Keep the output private because it contains deployment addresses. Identify the interface and route relevant to the chosen carrier path with the network owner.
These commands cannot tell you the full public NAT mapping or provider-side policy. Obtain those separately. If the host has multiple interfaces or policy routing, do not guess from the first displayed default route.
- Before you use it
- Run on the intended lab host; neither command changes networking.
ip -brief addressip routeCaptured demo response · 2026-09-23 21:35 UTC. Any filtering, hidden values or test-only data are identified in the capture label. Select Replay transcript to read the recorded output.
- Success looks like
- You and the network owner can identify the relevant local interface and route, then state the separately confirmed public/NAT mapping.
- Stop if
- Missing or unexpected routing, an unknown mapping or insufficient access leaves the carrier prerequisite unresolved; hand the observations to the network owner.
You should seeThe private handoff records local transport, socket, interface/route and separately confirmed public mapping with timestamps.
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6. Continue only when the handoff is complete
Open the carrier guide with an approved provider account and a reviewed test destination. Bring the observed transport/protocol/local bind, network mapping, installed versions and provider requirements. The carrier lesson must then verify its own signaling and media outcomes.
If your goal is only the course’s internal exercise, stay with its preflight and cleanup procedure. An internal Echo result, when actually observed, tests a different route from a public carrier call.
You should seeEither continue with a complete carrier prerequisite record, or name the missing value and its owner. No setting is changed by this page.
Open the scoped SIP carrier guide
Return to the internal practice-call preflight
- Installed host/driver/version and observation time recorded.
- Relevant local transport matches the socket for the same protocol.
- Public mapping and provider requirements are confirmed separately.
- Internal-call result is labeled from actual observations; no carrier outcome is inferred.
Checks and sources
What was checked
- This guide has dated terminal command replays, but no capture of a configured carrier, public NAT path or provider-side signaling exchange. Those states require the separate carrier exercise; a local transport or listening socket does not establish external call routing.
- Retained exact command captures establish only the dated lab transport, local UDP listeners and network observations shown. They do not demonstrate public reachability, provider authentication or a completed call.
- The linked current first-call lesson owns its preflight and observed outcome record; this recap makes no independent completed-call claim.
Primary references
Sources
- VICIdial open source contact center suiteVICIdial Group · accessed September 23, 2026
- Asterisk PJSIP troubleshooting guideAsterisk · accessed November 6, 2026