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How to resolve DTMF recognition issues on Ringover

  • Updated

DTMF (Dual-Tone Multi-Frequency) technology allows tones to be transmitted when you press keys on your keypad during a call. In this article, you will learn how to configure and troubleshoot your codec, routing, and network settings to ensure that your automated phone systems respond correctly to your keypad inputs.

 

1. Perform Basic Checks and Isolate the Issue

Before adjusting more complex configurations, perform isolation tests to target the source of the issue: 

  1. Press the keys on your keypad firmly during your calls. 
  2. Check that your general audio system is working properly. 
  3. Test sending tones from different devices such as the web app, the mobile app, and a SIP phone. 
  4. Make test calls to other phone numbers to determine whether the issue is general or related to a specific recipient. 

 

2. Configure Network Settings and Required Codecs

Poor network transmission or codec incompatibility prevents tone detection. Adjust these technical settings: 

  1. Set the DTMF transmission format to the RFC2833 standard on your equipment. 
  2. Disable the SIP ALG option in your router or firewall settings.
  3. Enable the NAT Keep-Alive setting to make the session more reliable. 
  4. Open the required telephony ports in your firewall (UDP SIP 5060 and the RTP range 10000-20000). 
  5. Prioritise the use of the G.711 codec to ensure signal fidelity.
  6. Temporarily disable compressed codecs such as G.729 and Opus to eliminate interference risks.

 

3. Adjust Ringover Settings and Routing 

Ensure that your call reception and routing environment on Ringover is properly set up:

  1. Use a physical SIP phone for maximum reliability if the web app controller is not responding. 
  2. Enable the DTMF input capture option in your switchboard routing settings to display the keys pressed by your callers.
  3. Remove any schedule restrictions configured on your user profiles.
  4. Thoroughly check the configuration of your Ringover switchboard.
  5. Enable line recording to allow audio analysis of the transmitted signals.
  6. Check the online availability status of the affected users. 

 

4. Send Diagnostic Information to Technical Support

If the issue persists after applying these steps, contact Ringover Support by providing a complete diagnostic file: 

  1. Note the precise Call ID affected by the detection error.
  2. Provide a detailed list of all the troubleshooting steps you have already performed.
  3. Describe the exact conditions under which the error occurs (caller and recipient numbers, exact timestamps, and types of devices tested).
💡 Tip: Always prefer a wired network connection (Ethernet cable) over Wi-Fi to guarantee stable transmission of voice packets and DTMF tones.
⚠️ Important : Using highly compressed codecs such as G.729 can distort the clarity of DTMF tones in in-band mode. Make sure to use the RFC2833 format (out-of-band) to bypass this limitation. 

 

🎉 You now know how to troubleshoot and configure your DTMF signals so that your automated phone systems respond perfectly to all your key presses!