You can set up a call-centre in minutes without any specialized software. Freshsales and Freshdesk’ in-built phone is powered by Twilio, our VoIP provider. 

When you are on a call, the voice data is transmitted over the internet via WebRTC or Flash depending on the browser. 

  • Chrome and Firefox support WebRTC. 
  • Internet Explorer and Safari do not support WebRTC yet, so they use Flash for data transmission instead.

Minimum Requirements

The following are the minimum requirements  to use the voice call features in phone channel.

  1. Network Requirements
  • Minimum 8kbps per agent per call. The more the better.
  • You can benchmark your network connectivity either in or in Our service provider recommends an "A" rating from pingtest for seamless voice data transmission.
  • Firewall
  1. Clients (Browser and App) should allow outgoing UDP connections to the public internet and allow return traffic in response. Since our service provider uses dynamic IP addresses, it is not possible to specify a range of IP addresses that requests go to.
  2. Clients (Browser and App) must allow incoming connections from and Also, they must be allowed to make outgoing connections from any port in the ephemeral range (1024-65535).

The following ports / port ranges must be opened in order to ensure the continued usage of voice services:

Phone channel on the browser


Component Address Client-side port used Server-side port used Protocol
Any 443 TCP
Any 443 TCP
RTP A dynamic IP pulled from Amazon's public range Any 10,000-20,000 UDP


Phone channel on the mobile app


Component Address Client-side port used Server-side port used Protocol
Any 10194 TCP
Any 443 TCP
RTP A dynamic IP pulled from Amazon's public range Any 10,000-20,000 UDP

Note: If your network policy mandates you to restrict network access, you need to make sure that you allow outgoing UDP and associated return traffic to any IP address in Amazon’s published range of public IPs. This range keeps changing, so you’d have to monitor and update these configurations as and when they change.

       3. Testing firewall and port configuration

  1. for a general scan
  2. for a UDP port scan.
  3. for a much more detailed network scan

For more details, refer  our service provider’s list of network connectivity requirements.

      4. Browser requirements

  1. The flash (fallback mode) supports Google Chrome 11+ (however, Flash is currently not compatible with Chrome incognito mode), Internet Explorer 7+, Safari 5+, and Firefox 3.6+ with Flash 10.1 or higher installed.
  2. WebRTC is supported in Chrome (v28+) and Firefox (v23+) on desktop. We do not support Android browsers. 

You can check if your browser is supported and configured correctly here.

     5. Other requirements

If your router includes SIP Application Level Gateway (ALG) function or Stateful Packet Inspection (SPI), disable both these functions.

Best Practices

  • Use ethernet and not WiFi. The wireless medium adds to the packet loss and can cause issues with call quality and hence must be avoided.
  • If you are using WiFi, reduce packet conflicts by reducing the number of devices operating on same channel.
  • Avoid transferring huge amounts of data in the same WiFi network as the voice because this can add to the latency.
  • Use high bandwidth internet connection as a lower bandwidth adds to the inherent latency involved in algorithmic processing, network traversal etc.
  • Local network conditions have the highest impact on voice quality. Make sure you have sufficient bandwidth and try using ethernet for voice data.
  • If you have addressed the above issues and continue to have jitter related impact on your voice quality, you may consider configuring your router with QoS rules to prioritize traffic on the UDP ports ranging from 10000-20000. (You can read this great article on setting up QoS for VoIP in your network.)
  • We recommend you use USB / 3.5mm headsets over bluetooth ones. Even while using bluetooth ones, it is better to connect to the USB dongle that comes with the headsets rather than rely on native bluetooth capabilities. This is because each browser behaves differently with different hardware vendors and it becomes impossibly difficult to troubleshoot such issues.

Steps to troubleshoot when you encounter problems with the phone channel

  1. Upgrade Browser and Flash to latest version.
  2. Ensure your network ports aren’t being blocked by Firewall / router / antivirus software. Check out the section “Firewall” under “Minimum Requirements” in this document for the ports to be opened.
  3. If your router supports QoS, prioritize UDP ports in the range 10000-20000, and the IP address of the sales reps making/receiving the calls. Tips on setting up QoS for VoIP in your network can be found here.
  4. Check your network latency with the Ping test site. If the grade is less than A, call quality might be degraded.

If Twilio Client cannot establish a call:

  1. Check open network ports in your router / firewall / antivirus software (step 2 in Steps to troubleshoot).
  2. Confirm if a network connection is currently available.
  3. Review the javascript console for application errors.

If no audio or one-way audio is experienced in a Client call: 

  1. Check open network ports in your router / firewall / antivirus software (step 2 in First Steps checklist).
  2. Confirm the hardware is correctly attached and ensure the correct microphone and speakers are selected in software settings.
  3. Check to ensure the microphone is not muted (some have a hardware mute button) and the speaker volume is turned up.
  4. If you are using a bluetooth headset, use a USB dongle instead of relying on the computer’s native bluetooth. Retry with a USB headset or a 3.5mm headset and compare the call quality. Since each device behaves differently with each browser, it can be more than a little trouble to tackle such hardware related issues.

If call audio has dropouts:

  1. Twilio Client requires a high speed and low latency network connection. Benchmark the network using or and aim to improve the scores.
  2. Enable router QoS or prioritize traffic for Twilio Client (step 3 in Steps to troubleshoot).
  3. Reduce network activity not related to VoIP or use a separate network for VoIP workstations.
  4. Chrome v38/39 has known issues of audio dropouts / one-way audio. Upgrade your browser or use Firefox and see if the issue persists.

If the call’s audio is garbled:

  1. Use an (analog) headset instead of built in computer microphone.
  2. Reduce ambient noise such as nearby speakers or fans.
  3. Adjust the distance of the microphone from the mouth – too close can cause audio clipping.
  4. Adjust microphone levels in the computer’s sound settings.
  5. Ensure computer has resources available to process a call:
  6. CPU and RAM are not over utilised
  7. Close unnecessary applications and browser tabs
  8. Try disabling the antivirus software