Figure 8-23: Fxo-Fxs Remote Pbx Extension (Example) - AudioCodes Mediant 800 MSBG User Manual

The following is required:
FXO interfaces with ports connected directly to the PBX lines (shown in the figure
below)
FXS interfaces for the 'remote PBX extension'
Analog phones (POTS)
PBX (one or more PBX loop start lines)
LAN network

Figure 8-23: FXO-FXS Remote PBX Extension (Example)

8.3.5.3.1 Dialing from Remote Extension (Phone at FXS)
The procedure below describes how to dial from the 'remote PBX extension' (i.e., phone
connected to the FXS interface).
To make a call from the FXS interface:
1. Off-hook the phone and wait for the dial tone from the PBX. This is as if the phone is
connected directly to the PBX. The FXS and FXO interfaces establish a voice path
connection from the phone to the PBX immediately after the phone is off-hooked.
2. Dial the destination number (e.g., phone number 201). The DTMF digits are sent over
IP directly to the PBX. All the audible tones are generated from the PBX (such as
ringback, busy, or fast busy tones). One-to-one mapping occurs between the FXS
ports and PBX lines.
3. The call disconnects when the phone connected to the FXS goes on-hook.
SIP User's Manual 438
Mediant 800 MSBG
Document #: LTRT-12804