Provides access to DTMF recognition services.
Assembly: Microsoft.Speech (in Microsoft.Speech.dll)
Dual-Tone Multi-Frequency (DTMF) tones are generated by pressing the keys on a telephone. The class supports the use of speech recognition grammars to analyze DTMF input emitted by telephones. The members of are similar to those of the SpeechRecognitionEngine class. However, the input for recognition consists of a series of DTMF tones instead of an audio stream.
The works by performing a series of emulated recognitions. It maintains a buffer with a list of tones that have been received. Every time a new tone is received, it appends the new tone to the list and emulates recognition of the whole list. This process continues until emulation produces a definitive result, or one of the timeouts is reached.