Reference10:Interfaces/FXO/Physical

The physical settings of the analogue FXO interfaces can be made here:

Receive gain:	Set the loudness a user receives at this interface. Defaults to 0dB, range -6dB to 2.5dB.
Transmit gain:	Set the loudness a user transmits at this interface. Defaults to 0dB, range -6dB to 2.5dB.
Flashtime:	Define the duration of flash-hook signal generated by the FXO on demand of the voip peer side. Possible values : 100ms, 200ms 300ms, defaults to 300ms.
Country:	Set the line impedance for different countries. 'GlobalImpedance' is intended to be used with countries that are not present in the list and that have no known similarities to mentioned countries.

Receive and transmit side

FXO Gateway representing phone	::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::direction:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::	central office/PABX
phone speakerphone	<<<<<<<<<<<<<<<<<<<<<<<<<<<<<----receive direction----<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<	PCM DAC
phone microphone	>>>>>>>>>>>>>>>>>>>>>>>>>>>>>----transmit direction---->>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>	PCM ADC

Explanation of Flash and R

Flash and R are used as equivalents. Sometimes hook-flash is also used. Often phones have an R key, but the meaning is all the same.

From a technical point of view Flash is a short interruption in offhook loop-current. You can imagine Flash as a very short hook-on/hook-off event. The on-hook duration of a Flash event is normally between 100ms and 300ms. A Flash on the FXO port will be performed only when the connected voip peer sends a special rtp-dtmf digit code 16d/10h. A flash can only be generated in the connected state, when both sides can hear each other. Flash or R can never be part of a dialing number, like sometimes seen on fax machines.

The innovaphone FXO ports do NOT support dialing with pulses.

Pinout of the a/b connector

Pin	Function
3	TIP
4	RING