DAHDi Config - Channel Breakdown Question

At the moment I have an E1 link to our Alcatel system that’s set to use all 30 channels.

In the next few months I’m going to be switching the Alcatel off and moving our ISDN external link to this card.

However our ISDN is only 22 channels. I’ve had a look to see what would be involved and when I change the dropdown from 30 to 22 is then appears with another option for the remaining 8 putting them into group 1 with a context of from-digital

The problem here is that I also have an 8 line Sangoma analog card for some backup PSTN lines. I have it configured for 4 lines in group 1 and 4 lines in group 2

Do I have to define the remaining unused ISDN channels? - Perhaps put them into group 4 then forget about them?

The above is using the DAHDi configuration module

FreePBX 64-bit 2.11 Asterisk 11

I think you dot need to put it as unuse channels. you are mixing the E1+analog cards, you have to reconfi sangoma cards and in dial plan, you can point to the analog channels if there are some call routes.
Of course, you also can put the channels as unused channels, but i do not think it will affect you logic. the dialplan and chan_daid are quite flexible. you can route the calls to any particular channels or groups.

Dahdi will enumerate all the channels found consecutively on startup card by card, (you can change that by manipulating udev if you need to), the underlying /etc/dahdi/system.conf does not care about missing channels used in /etc/asterisk/dahdi.conf but they must all agree with your hardware channels defined in system.conf an E1 is always an E1 with 31 channels the analog card also to suit the card and not the modules present, and those used must exist and be defined with appropriate signalling. and neither does asterisk care about missing channels. The same goes with groups, they are arbitrary, if the dahdi helper module constrains that ( I doubt it) , then just disable it after it did it’s grunt work and manually adjust what is in your /etc/asterisk/dahdi.conf files to suit your new fractional E1 to suit what b-channels your provider allows.