To ensure that every call made and received from Freshcaller is of best quality, there are certain best practices and troubleshooting norms that you should follow. 

By running the following sanity checks, most issues related to call quality and transmission can be sorted. 

Let’s begin by understanding the most common call issues that a cloud call center software user faces. And more specifically what we at Freshcaller have noticed as the most common concerns.

These concerns can be classified into the following categories:

  1. Unable to establish a call from Freshcaller    
  2. Lack of audio or one-way audio
  3. Call audio gets terminated midway or stops transmitting
  4. Call audio is garbled or contains artifacts

There could be multiple reasons for all the above scenarios to hinder a clean call experience.. The below step by step troubleshooting cues can help you weed out the most basic issues instantly. 

Network Connectivity Test 

This helps you identify and troubleshoot all network related concerns proactively.


  • Test diagnosis: Make sure that you clear all the tests under this network test diagnosis. (Note: Video tests are an exception)

  • Handling network failure instances: If any of the tests fail, it might be indicative of certain firewall restrictions blocking Twilio from communicating with the internet. Here, TCP, UDP or both of these would have failed.   

  • The best way to go forward is to whitelist all the IP addresses and open the ports that are mentioned by Twilio. The list of these ports and IP addresses is listed below in this article.

  • ICE error: Next is the ICE error which is the most common issue that you might encounter. (In this scenario, your call will be disconnected within 10 secs. The possible solution for this is to Whitelist the IPs and to open up the respective ports.

  • Next step is to check the number of simultaneous Twilio connections that Twilio can support within your network. For example, if a team of 20 users use Freshcaller at the same time and if the result shows that Twilio supports only 12 simultaneous calls, there would be time lags, call quality issues, one-way audio issues and high possibility of call drops.

  • Ensure that the network test is run on every agent’s local machine, and specifically make it mandatory for ones who report facing call quality issues

  • You also need to check if the local machine is connected through LAN or the wireless channel (LAN is always the preferred option).

  • Please increase the network bandwidth if needed. This is a crucial step that would solve most of your call quality issues

  • Also, please do check if there are other applications(of lesser priority like Youtube, Chrome, etc.) consuming the available bandwidth. If that’s the case, please ask your network/IT team to deprioritize the other applications and give maximum priority to call and call related activities to have a smooth call experience.

  • Check for possible Jitter and Packet loss issues( Ideally, there should be zero packet loss and jitter should be less than 3s). Understand how to solve this in detail from here.

  • While all the above mentioned precautions are to be considered important, you can ignore “Group Room failed errors” since they are common and not a big issue.

  • The test will also ask you to enable your microphone. If you don’t allow your microphone to be tested, an error message will be thrown by the test.

Network Speed Test

Check the network speed using and send a screenshot with the results to

  • If the router supports QoS, prioritize the ports mentioned below, or the IP address of the computer(s) making the client calls.

  •  Even after completing the above steps, if you face call quality issues, you need to make note of the following call details:

            - FROM number

            - TO number

            - Actual time of the call

 and share it over an email to

IP’s and Port’s to be Whitelisted in case of Firewall restrictions 

The firewall should allow outgoing UDP to the public internet from the browsers that use Freshcaller, and allow return traffic in response.



Server-side port used †


Signaling - GLL

(Global Low Latency)



Signaling -



(Regions: au1, br1, de1, ie1, jp1, sg1, us1)




Static IP range *

10,000 - 20,000





For the static IP range for UDP, please open up the traffic to the following CIDRs. You have to open up traffic to all the CIDRs mentioned below. Twilio will dynamically connect to one of these IP ranges depending on the browser location.

Region ID


Media Server IP Address Range

CIDR notation


Australia - -


Brazil - -


Ireland -, -,


Frankfurt - -


Japan - -


Singapore - -


US East Coast (Virginia) - , -,

us US West Coast (Oregon) -

Region ID


Media Server IP Address Range

CIDR notation

Port Range


US East Coast (Virginia) over Interconnect exchange in Virginia -

443 (Signaling), 10,000 - 20,000 (Media)


US West Coast (Oregon) over Interconnect exchange in San Jose -

443 (Signaling), 10,000 - 20,000 (Media)


Ireland over Interconnect exchange in London -

443 (Signaling), 10,000 - 20,000 (Media)

de1-ixFrankfurt over Interconnect exchange in Frankfurt -
443 (Signaling), 10,000 - 20,000 (Media)
sg1-ixSingapore over Interconnect exchange in Singapore -
443 (Signaling), 10,000 - 20,000 (Media)

Best practices to have a great call experience 

1. Browser preference: Use a Chrome/Firefox browser

2. Channel preference: Use LAN wired connection instead of wireless

3. Headset preference: Opt for a high-quality wired headset

4. Modem preference: Go for a modern, well-equipped PC with sufficient RAM

5. Try to have a moderate tab usage (too many tabs eats up your RAM)

6. Don’t run other processor-intensive applications in parallel to Freshcaller

7. Reduce ambient noise such as nearby speakers, fans, exhaust, etc.

8. Adjust the distance of the microphone from your mouth - having it too close to your mouth could cause audio clipping.

9. Adjust the microphone levels in your computer’s sound settings

10. Ensure that your computer has resources available to process a call

11. Try disabling any antivirus software if installed.