ReceiveSF()

Since 16.24.0, 18.10.0, 19.2.0 Applications

Detects SF digits on a channel and saves them to a variable.

Last reviewed 2026-04-14

ReceiveSF(variable[,digits,timeout,frequency,options])

Dialplan Builder -- build your ReceiveSF() command

variable

The input digits will be stored in the given *variable* name.

digits (optional)

Maximum number of digits to read. Default is unlimited.

timeout (optional)

The number of seconds to wait for all digits, if greater than `0`. Can be floating point. Default is no timeout.

frequency (optional)

The frequency for which to detect pulsed digits. Default is 2600 Hz.

options

d: Delay audio by a frame to try to extra quelch.

Delay audio by a frame to try to extra quelch.

e: Allow receiving extra pulses 11 through 16.

Allow receiving extra pulses 11 through 16.

m: Mute conference.

Mute conference.

q: Quelch SF from in-band.

Quelch SF from in-band.

r: "Radio" mode (relaxed SF).

"Radio" mode (relaxed SF).

Full arguments reference

variable required - The input digits will be stored in the given variable name.
digits - Maximum number of digits to read. Default is unlimited.
timeout - The number of seconds to wait for all digits, if greater than 0. Can be floating point. Default is no timeout.
frequency - The frequency for which to detect pulsed digits. Default is 2600 Hz.
options
- d - Delay audio by a frame to try to extra quelch.
- e - Allow receiving extra pulses 11 through 16.
- m - Mute conference.
- t - Post-digit timeout, in seconds. If more than this amount of time elapses after a digit, the number will be deemed finalized and the application will return This is useful when reading a variable number of digits that is unknown in advance. This can be almost any positive decimal number of seconds, but must be no less than 0.6 seconds, since this is the SF inter-digit timeout. The default is 0.8, which should be compatible with SendSF. Values lower than 0.75 will generally produce unreliable results. Note this timer only kicks in after at least one digit has been received, to account for sender/receiver synchronization. Note that RECEIVESFSTATUS will still be set to TIMEOUT if the post-digit timer expires.
- q - Quelch SF from in-band.
- r - "Radio" mode (relaxed SF).

Description

Reads SF digits from the user in to the given variable.

This application does not automatically answer the channel and should be preceded with Answer or Progress as needed.

RECEIVESFSTATUS - This is the status of the read operation.
- START
- ERROR
- HANGUP
- MAXDIGITS
- TIMEOUT

Arguments

variable required - The input digits will be stored in the given variable name.
digits - Maximum number of digits to read. Default is unlimited.
timeout - The number of seconds to wait for all digits, if greater than 0. Can be floating point. Default is no timeout.
frequency - The frequency for which to detect pulsed digits. Default is 2600 Hz.
options
- d - Delay audio by a frame to try to extra quelch.
- e - Allow receiving extra pulses 11 through 16.
- m - Mute conference.
- t - Post-digit timeout, in seconds. If more than this amount of time elapses after a digit, the number will be deemed finalized and the application will return This is useful when reading a variable number of digits that is unknown in advance. This can be almost any positive decimal number of seconds, but must be no less than 0.6 seconds, since this is the SF inter-digit timeout. The default is 0.8, which should be compatible with SendSF. Values lower than 0.75 will generally produce unreliable results. Note this timer only kicks in after at least one digit has been received, to account for sender/receiver synchronization. Note that RECEIVESFSTATUS will still be set to TIMEOUT if the post-digit timer expires.
- q - Quelch SF from in-band.
- r - "Radio" mode (relaxed SF).

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