Voicetronix Programming Guide
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# DTMF and Programmable Tone Generation

The following functions support tone generation on the VPB:

`vpb_dial_async()`
`vpb_dial_sync()`
`vpb_settone()`
`vpb_gettone()`

Tones (including DTMF) tones are generated on a channel using the `vpb_settone()` function. All of the standard DTMF tones are defined at initialization. Other user defined tones can be programmed at any time using the `vpb_settone()` function. The standard DTMF tones can also be reprogrammed using the `vpb_settone()` function. The tone generator parameters are constant across all VPB channels, they are not programmable on a channel by channel, or board by board basis. Up to 10 programmable tones can be defined, giving a total of 26 tones including the standard DTMF tones. Each tone can consist of up to 3 frequency components, each with independent amplitude, specified in dB with respect to the overload level of 0dB. There are limits in the tone generator parameters. Attempting to program a tone outside of these limits will generate an error.

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Playing and Recording Audio |  | Tone Detection