; fxo_ks: FXO (Kewl Start)
; pri_cpe: PRI signalling, CPE side
; pri_net: PRI signalling, Network side
+; sf: SF (Inband Tone) Signalling
+; sf_w: SF Wink
+; sf_featd: SF Feature Group D (The fake, Adtran style, DTMF)
+; sf_featdmf: SF Feature Group D (The real thing, MF (domestic, US))
+; sf_featb: SF Feature Group B (MF (domestic, US))
; The following are used for Radio interfaces:
; fxs_rx: Receive audio/COR on an FXS kewlstart interface (FXO at the channel bank)
; fxs_tx: Transmit audio/PTT on an FXS loopstart interface (FXO at the channel bank)
; em_tx: Transmit audio/PTT on an E&M interface (1-way)
; em_txrx: Receive audio/COR AND Transmit audio/PTT on an E&M interface (2-way)
; em_rxtx: same as em_txrx (for our dyslexic friends)
+; sf_rx: Receive audio/COR on an SF interface (1-way)
+; sf_tx: Transmit audio/PTT on an SF interface (1-way)
+; sf_txrx: Receive audio/COR AND Transmit audio/PTT on an SF interface (2-way)
+; sf_rxtx: same as sf_txrx (for our dyslexic friends)
;
signalling=fxo_ls
;