SIP Call Ladder | Synthflow

Synthflow AI provides a SIP Call Ladder feature, which allows detailed technical analysis of your calls by displaying the SIP signaling flow and allowing you to download packet capture files for deeper investigation.

This tool is useful for:

Troubleshooting call failures by examining the SIP signaling at a glance.
Understanding call flow between different network elements for full transparency on the Synthflow AI network.
Debugging connectivity issues with detailed packet analysis and the ability to download a pcap.
Self-service problem resolution without needing to contact support.

Accessing SIP Call Ladder

Navigate to the Logs section in your workspace. For more information about Logs you can learn more here

Select any call from your call logs to view its details.

Click on the SIP Ladder tab to view the SIP signaling diagram.

Understanding the SIP Ladder Diagram

The SIP ladder diagram shows the complete signaling flow between different network elements involved in your call:

Vertical lines represent different network elements (your agent, our network hops, SIP carrier)
Horizontal arrows show SIP messages flowing between elements
Message types include INVITE, 100 Trying, 180 Ringing, 200 OK, BYE, etc.
Timestamps help you understand the timing of each signaling event

This visual representation should make it easier to view and debug SIP signaling at a glance, for anything else we provide an option to download the SIP pcap file itself.

Call quality

The Telephony tab also reports the media quality of the call, derived from RTCP. Use these metrics for a first read on a “the audio was choppy” report before you download a PCAP.

Metric	What it tells you
MOS	Mean Opinion Score from 1.0 to 5.0, estimating how the call sounded overall. Target above 4.2.
Round-trip time	How long audio takes to reach the far end and come back, in milliseconds. Target under 100 ms for regional traffic.
Jitter	Variation in packet arrival time, in milliseconds. High jitter is what makes speech sound robotic or choppy.
Packet loss	Share of audio packets that never arrived, as a percentage.

A metric shows a dash when it could not be measured, which happens when the remote endpoint sends no RTCP (common on the carrier leg) or when the media did not pass through our media relay. A dash means the value is unknown, not zero.

For target ranges, how each metric affects what the caller hears, and how to measure them from your own network, see Performance Metrics.

The same measurements are available per call through the API as telephony_rtp_* fields on Get a call and List calls, reported separately for the WAN (carrier) and LAN (internal) legs.

Downloading PCAP Files

For advanced troubleshooting, you can download the complete packet capture (PCAP) file for any call. Please be aware you will need a program to view .pcap files, we recommend Wireshark for this.

From the SIP Ladder tab, locate the Download PCAP button.

Click to download the PCAP file to your local machine.

Use tools like Wireshark to analyze the packet capture file for detailed network analysis.

Troubleshooting Common Issues

When analyzing SIP ladder diagrams, look for these common patterns:

Issue	SIP Ladder Pattern	What to Check
Call Not Connecting	INVITE sent but no response	Check the agents number, specifically SIP Domain if you add your own numbers.
Call Drops	Unexpected BYE message	Check for network timeouts or carrier issues
Authentication Failures	401 response	Verify SIP credentials and account permissions
Authentication Failures	403 responses	Verify SIP credentials and calling permissions
One-Way Audio	200 OK received but RTP issues	Verify media codec compatibility, source and destination IP’s and firewall settings

Getting Additional Help

If you’re unable to resolve issues using the SIP ladder and PCAP analysis:

Check the Telephony Errors page for specific error code explanations.
Review your number configuration and the call settings for correct formatting.
Contact support with the PCAP file and SIP ladder screenshot for advanced troubleshooting along with the URL of the agent so we can help.