Teams calls, SIP flow and captures

What it is for

When a call from Teams does not arrive, ends too early or has no audio, you need the exact sequence of events. EasyUC offers four tools of increasing depth: the list of running calls, the call history with a SIP ladder diagram per call, the SIP trace of the whole tenant and the network capture as a pcap file.

The call history stores, for every call, all SIP messages between Microsoft and the EasyUC SBC, without the periodic OPTIONS. The ladder diagram shows them in chronological order with arrows. You see at a glance who gave which answer. Keys for audio encryption are redacted before storage.

The SIP trace additionally records the OPTIONS and everything else of the tenant. The network capture writes the packets themselves. The leg to Microsoft is encrypted in it and not readable; only the internal leg between SBC and EasyUC is readable.

Prerequisites

• Licence module teams. Without this module the EasyUC Teams workspace does not appear.
• Role EasyUC Teams (ROLE_APP_TEAMS_WORKSPACE) with the sub-permission TENANTS (ROLE_APP_TEAMS_TENANTS). To switch and delete, also TENANTS bearbeiten (ROLE_APP_TEAMS_TENANTS_EDIT).
• For the SIP flow of past calls: Save the SIP flow of every call was switched on at the time of the call, and the retention period has not expired.
• For the network capture: the SBC service is running and reporting in. At most two network captures run on the SBC at the same time.
• A program such as Wireshark to analyse a pcap file.

Step by step: Examine a call in the call history

1. Open Teams Tenants, click the tenant and select Call history in the tenant bar. The page opens filtered to this tenant.
2. Narrow the period with Date from and Date to.
3. Under Direction, choose inbound or outbound.
4. In Search, type the number, the dialled number, the Call-ID or the UUID and confirm with the magnifier button.
5. Click the row of the call. The SIP flow page opens.
6. Read the header: Tenant, Direction, From, To, where applicable Pilot, State, Codec, Remote IP, Start, Duration and SIP Call-ID.
7. Read the ladder diagram from top to bottom. Microsoft is on the left, the EasyUC SBC on the right. Messages with SDP carry the label SDP.
8. Click a message to see its content. The arrow keys move the selection. Copy puts the text on the clipboard.
9. Click Download SIP flow (.txt) if you want to pass the sequence on.

Step by step: Watch running calls

1. Select Show calls in the tenant bar. The number on the menu item is the number of running calls.
2. For each call, read Direction, From, To, State, Codec, Remote, Duration and Call-ID.
3. Click a row. The SIP flow opens and refreshes every 2 seconds while the call is running.
4. If it says “No call running through this trunk right now.”, place the test call and wait a moment.

Step by step: Record a SIP trace of the tenant

1. In the header of the tenant page, click Start SIP trace. The notice SIP trace is running appears with the end time. The trace ends by itself after 30 minutes.
2. Place the test call.
3. Select SIP log in the tenant bar.
4. In Filter, type for example INVITE, a number or a Call-ID.
5. Click an entry to expand the complete message.
6. Click Download log for a text file or Export pcap (TranslatorX/Wireshark) for a pcap file. If the filter narrows down to one Call-ID, the pcap file contains only that call.
7. Click Stop SIP trace in the header when you are done. Clear deletes the tenant’s log.

Step by step: Record a network capture (pcap)

1. Select Captures in the tenant bar.
2. Under Capture for, choose the duration: 5, 10, 15, 30 or 60 minutes.
3. Under At most, choose the file size: 50, 100, 200 or 500 MB.
4. Tick Include the internal leg to EasyUC only if you need SIP and audio in clear text. Read the warning: the file then contains the calls of all tenants on this SBC.
5. Click Start network capture and confirm the prompt if one appears.
6. Wait for Network capture is running and place the test call.
7. Click Stop network capture or wait for the end.
8. The file appears in the list as soon as the SBC has transferred it. Until then it shows Being transferred.
9. Click the download icon in the row. The bin icon deletes the file.

Fields and options

Check the result and narrow down errors

• Success: the test call is in the call history, and the ladder diagram shows INVITE, 200 OK and BYE.
• The call is missing from the call history: Teams did not send it over the EasyUC trunk. Check whether the EasyUC policy is assigned to the caller, whether the number is listed as Reachable under Scripts over this trunk and whether Routes in Teams shows Up to date.
• “SIP flow recording is off for this tenant” Switch on Save the SIP flow of every call in the tenant settings. Calls that begin afterwards are stored.
• “No SIP messages were stored for this call.” The flow was off during the call or has been deleted after the retention period.
• No audio or audio in one direction only: check Public IP and Media IP on the SBC page and the UDP rule for the RTP range. Successful OPTIONS only prove the signalling path.
• The call ends about 10 seconds after being answered, without audio: the script runtime delivers no audio to the SBC. Check that the script is enabled and that the script runtime service is running.
• Teams reports a failed call to a script number immediately: the script is unknown, switched off or not Reachable via MS Teams, or the script runtime does not answer.
• “The SBC has not confirmed the network capture yet.” or “Network capture not available: …” The SBC service is not reporting in or the capture component is not running. Check the service in the EasyUC Manager.
• „Es laufen bereits 2 Netzwerk-Mitschnitte auf anderen Tenants. Bitte einen davon beenden oder sein Ende abwarten.“ Stop one of the running captures.
• “The SIP trace is off. Turn it on above to record what goes over this trunk.” The SIP log is empty as long as no trace has run.
• Captures contain phone numbers and, with the internal leg, call content. Pass them on only to the intended recipient.
• A running call counts as ended when the SBC has not reported it for two minutes. Until then it carries the label Live.
• With Operator Connect through Teams forwarding, the INVITE in the ladder diagram shows the History-Info header with the Operator Connect number. The call history therefore also stores the sign-in name of the forwarding service account. It is subject to the same retention period.
• Read the flow as in the chapter on the SIP ladder diagram: first INVITE, last response to it, BYE. A red response from the SBC names the reason on the EasyUC side, a red response from Microsoft the reason in the tenant.