Backup and Restore module, is backup restorable with similar servers?

Hi I've got a trixbox CE 2.6.1 server with a
Digium TE122 T1/E1 Card
TDM800P Card
I have done a backup using the optional 'Backup and Restore' module.

I copied the backup to another trixbox CE 2.6.1 server with slightly different hardware:
Digium TE110P T1/E1 Card
TDM400P Card

After running the restore everything appeared correct, extensions, outbound rules, inbound rules, IVR, etc etc all looks good.
When I call internally all is working fine, but when I tried to call outside I got the dreaded "all circuits are busy".
I ran "setup-pstn" again and that didn't fix it, I also rebooted and that didn't fix it.

Could this be because I did a restore and there is somewhere where the hardware is included in a config, thus making the backup incompatible?

Thanks,