Run a CScan Test

Use CScan with the Port Reference Information for Cisco Webex Calling to ensure that all required firewalls are in place.


From the customer view in, go to Quick Links and select Webex Calling Network Readiness Tool.


You can also access the CScan tool by going to


Select a location, choose the language, and click Pick server.

Choose the location that is closest to you. This will be the data center that Webex Calling will connect to.


Choose between:

  • Advanced Diagnostic Test
  • Basic Test


If you choose Advanced Diagnostic Test, you must allow CScan to access your microphone and camera.


Select Start Test.

CScan Report Information

Basic and Advanced Diagnostic Tests

The Basic Test analyzes the following between your computer and the Webex Calling data center:

  • Download and upload bandwidth

  • Latency

  • Traceroute reports

  • TCP ports*

* The TCP ports that are tested are a subset of the ports required for Webex Calling. It isn’t possible to test all the ports for a web-based application. Follow the port requirements guide to ensure that your firewall is set up correctly.

The Advanced Diagnostic test analyzes the same information as the Basic test but adds:

  • Packet loss (download and upload)

  • Jitter (download and upload)

To carry out the Advanced Diagnostic test, CScan must open a WebRTC connection to your computer, this requires access to your computer’s camera and microphone. CScan doesn’t save any audio or video packets. This permission is used for measuring packet loss and jitter. CScan will never access your camera or microphone outside of running a test. The permissions can be revoked at any time.

Traceroute Report

A traceroute report is provided when you run a CScan test. To generate this, CScan initiates a traceroute from a Webex Calling data center to the public IP address of your computer. This can give insight into where issues might be occurring along the path between your computer and the Webex Calling data center. Traceroute reports can take a while to generate. The link is dimmed until the report finishes generating.

Interpret Test Results

The CScan tool estimates potential concurrent calls that could traverse your network. This is an estimate based on the bandwidth that is required for audio calls, allowing for a buffer of extra internet traffic. Since the CScan test is taken at a single point in time, this is an estimate and not a guarantee of performance during peak traffic times.

If CScan indicates that ports are blocked, check your firewall configuration and the port requirements document. If ports are blocked, you may have issues registering devices or making calls. It's not possible to test all ports listed in the Port Requirements document, so if all ports on CScan are listed as open, there may still be other ports not tested that are causing issues.

If latency or bandwidth figures are low, you may have a lower quality Webex Calling experience. Ensure you have enough bandwidth from your ISP, and that your device has a strong connection to the internet. If you’re using Wi-Fi, ensure that your signal is strong.