Error 0x8004001D

Value: -2147221475 | 0x8004001D | 2147745821

What does it mean ?

TAPI_E_INVALTONE  
Invalid tone.
Value: 29 | 0x001D | 0b0000000000011101

Where does it come from ?

FACILITY_ITF  
COM/OLE Interface management. FACILITY_ITF is designated for user-defined error codes returned from interface methods
Value: 4 | 0x004 | 0b00000100

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