written by ADMIN MANAGEMEN at 2016-02-28

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As usual, we can connect the PABX with the VOIP device by the FXS or FXO, and how does the call work? here we will describe the different connections will have the different methods for dialing.

Connection A: FXO of PABX connects with FXS of voip gateway.

Here it is the outbound call of PABX.

When the extension 7001 wants to dial the extension 8001, 7001 needs to dial 9+8001, here we 

assume 9 is the prefix which is used to call out through the FXO in the PABX, after that, the call will be

transferred to voip gateway.

Here it is the inbound call of PABX.

When the PABX receives the call from 8001 through the FXO, 8001 will hear the second dial tone firstly,

then 8001 can go on dialing 7001, so 7001 will ring directly.

Connection B:FXS of PABX connects with the FXO of voip gateway.

Here it is the outbound call of PABX.

7001 will dial 7002 firstly, then the call will reach the FXO of voip gateway, 7001 will hear the second

dial tone, 7001 can go on dialing the number 8001.

Here it is the incoming call of PABX.

After the PABX receives the call through the FXS 7002, 7001 will ring directly.