might you describe exactly what the ‘issue’ is? to further troubleshoot, you should add “dtmf” to your logger options for either the console or asterisk log file. It will give some good information about what’s happening.
When it works the Background app gets the DTMF digits and does what it is suppose to. When it does not work, the audio file played by Background just keeps on going when a DTMF digit is entered.