If the Dual Tone is clearly heard at a telephone under test, but the DTMF Receiver for thattelephone does not respond, where is there likely to be a fault?

If the Dual Tone Multi-Frequency (DTMF) is clearly heard at a telephone under test, but the DTMF Receiver for that telephone does not respond, the fault is likely to be in the DTMF Receiver itself.

Here are the steps to identify the fault:

1. Check the DTMF Receiver: The DTMF Receiver is responsible for interpreting the dual tone signals into the corresponding numbers or symbols. If it's not responding, it might be faulty or not properly connected.

2. Test the DTMF Receiver: You can do this by using another telephone that you know is working properly. If the DTMF Receiver works with the other telephone, the problem might be with the telephone under test.

3. Check the connection between the telephone and the DTMF Receiver: If both the telephone and the DTMF Receiver are working properly individually, there might be a problem with the connection between them. Check the wires and the ports to make sure they are properly connected and not damaged.

4. Check the telephone settings: Some telephones have settings that can affect the DTMF signals. Make sure that these settings are correct.

5. If all else fails, consult a professional: If you've checked everything and the DTMF Receiver still doesn't respond, it might be best to consult a professional. They will have the tools and knowledge to diagnose and fix the problem.