4 FXO and 2 analog PSTN lines


My config :
Sangoma appliance Freepbx 13
2 sangoma A200-O FXO Module (2 Ports)
2 PSTN analog lines.

I tried to understand DAHDI, trunk and outbound route and use one or the other of my PSTN line.
I already have one outbound route that works well but it seems to use the PSTN line 1 or line 2.
(I know that because when I unplug one or the other PSTN line it work).
I tried to get an outbound route that use only line 2

In Connectivity – DAHDI Config :
for all ports I got:
Signaling: kewl start
Group: 0
Context: from-analog

Do I have to put each port in a different group ? so : 0 1 2 3

in Trunk – DADHI settings – DAHDI Trunks I got choices:
Group 0 Robin Ascending
Group 0 Ascending
Group 1 Round Robin blabla
Analog Channel 1
Analog Channel 2
Analog Channel 3
Analog Channel 4

Do I have to configure the Trunk with a group or with an analog Channel ?
I tried both but groups work better.

With an analog Channel, it seems that this parameter is overwrite and go back to : Group0 Round Robin each time I hit “Apply Config”

I believe I misunderstood something important.

Thanks for your help