Isolate the reason a phone device is unreachable

Christina Dechent
Christina Dechent
  • Updated
If a babelforce call fails to receive a response from an agent phone device, we will label this outcome as "unreachable".
This can be caused by the traffic not always getting through the router, the firewall of the router, the firewall on the computer/device that the softphone is installed on, the softphone being frozen, the operating system on the computer/device not responding, a loss of internet connection (even briefly) and a few other reasons.
When this happens, we mark the call as "unreachable" in the call logs. We also show the agent that they were "unreachable" on the last attempt and we present a feedback message and a reset button. It will look like this:
If the agent resets, the unreachable status is set back, so that calls will try to reach the agent again. If the problem was just intermittent, e.g. device did not respond, or brief connection loss to the router, etc., calls reach the agent again after the reset.
If the issue persists, you can isolate the source of the problem as follows:
To troubleshoot - go through the steps here and do a test after each case.
First verify again that the issue occurs: 
0a. do test call that is routed to the agent and verify that you receive the message "unreachable".
0b. call the softphone directly using the babelforce Agent ID Number (SIP ID) 999xxxxxxx number from another phone/softphone connected to another babelforce SIP account.
These tests will verify that the issue is currently continuously occurring.
Next, make one change at a time and isolate: 
Do each of these changes and test inbound call after each step. 
Note that it is vital to try to test just one change at a time.
  1. restart the softphone
  2. restart the computer/device (if you installed the softphone on a computer, turn off the firewall on the computer for a test)
  3. connect to a different network, e.g. switch from one Wi-Fi network to another, switch to LTE/mobile data with no Wi-Fi, switch to wired connection
  4. restart the router
If you go through these steps in order and test with a call afterwards, you will get closer to isolating where the issue could be that causes the issue. If you locate a change where observed behavior switches from "unreachable" and starts working, then you might be on to something.
Try to reverse the change and repeat to isolate reliably
If it is technically possible for the particular change, reverse the step again and verify that the issue reoccurs. For example, if it is a switch from LAN to LTE, switching back would most likely reliably cause a reoccurrence.
After doing that, you could look at how to improve the end-to-end route to solve the issue. The solution will depend on the isolated issue.
For example, the rules in the firewall, the network traversal method used or another action if the problem occurs at a different part of the route.
Our section on Technical Network Requirements has more detailed information on how things should be set up in your network to achieve high quality voice calls.
If you have issues isolating the problem following the steps above or if you cannot find a solution, please contact us at
For us to investigate, we will most likely need the detailed outcomes of the above tests.

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