Connection declined – or ICE- is a network error. Twilio is reporting that the internet connection is failing. If your users see this message you want then to test the internet connection. You can check it here, and we also give this in the widget for the end-user to test her internet connection.







You want to test all four options:

  • Under Twilio Client Test Call
  • Bandwidth
  • Under Network UDP
  • TCP

In this example, you can see that the network is not sufficient for softphone calls. You want to see 2-3 times as many users as you have on the phone. If you have 10 users, you want to see bandwidth to support 20-30 users. Fastcall works best on a strong wired internet, with a high quality headset.

When a call is connected using the Fastcall softphone – which uses Twilio client – periodic messages verify that the call is alive. If these message exchanges fail, it could indicate a problem with the connection to Twilio.

‘ICE liveness checks failed’:  the browser had trouble keeping the media session active. The call should continue, but the network connectivity may have degraded.

‘ICE negotiation with Twilio failed’: The browser made a TCP connection to Twilio, but could not establish UDP/RTP media connectivity. This can happen if network connectivity is poor, or if UDP is being blocked, or if a network policy prevents UDP to/from IP addresses in Amazon’s public range. When this error occurs please ensure that the Twilio client network connectivity requirements are taken into consideration.


What is the required firewall configuration when using the softphone?

Your firewall should allow outgoing UDP to the the public internet from the browsers that will be using Twilio Client and allow return traffic in response. Twilio does give advanced instructions on how to prioritize calls through the router. These calls are using the office internet. If bandwidth is low, even temporarily because of other activities in the office, calls will suffer. These are not application errors.

Visit Twilio page for more detail

Get to know: Advanced instructions for your network administrator.