DAHDI oddity


#1

The chan_dahdi_groups.conf signalling value is backwards from GUI my settings. Channel 1 and 2 are FXO s and 3 and 4 are FXS. Curious.

signalling=fxs_ks
context=from-analog
rxgain=1.1
txgain=1.1
group=0
channel=>1

signalling=fxs_ks
context=from-analog
group=0
channel=>2

signalling=fxo_ks
context=from-analog
group=1
channel=>3

signalling=fxo_ks
context=from-analog
group=1
channel=>4


(Lorne Gaetz) #2

Signalling is correct. It’s opposite to the port.

/Shrug


#3

If you have a Bell-shaped head, it makes sense. Consider an old school FX (Foreign eXchange) line. The FXS (Foreign eXchange Station) device is at the customer end and one side connects to a phone. But the other side (connected to the carrier facility) is communicating with the FXO (Foreign eXchange Office) device, i.e. using FXO signalling. Likewise, the FXO box in the CO is communicating with the customer’s box using FXS signalling.

It’s the same ‘logic’ as why we buy termination to make calls and origination to receive them.


#4

Interesting and somewhat expected. Thanks for the explanation. Noticed it while wrestling with DAHDI gains.


(Dave Burgess) #5

Thanks for that. This has always been my favorite part of phone-speak. “It’s not backwards, from our perspective it makes perfect sense.”


(system) closed #6

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