Try:
fwconsole stop
fwconsole chown
fwconsole start
If no luck, reboot server, look for any relevant errors in
/var/log/messages
Next, see DAHDi Doesn't appear to be running , especially the last post.
If still no luck, you might try restoring from a recent backup. If you don’t have one, consider making a backup (so you can get back to where you are now), then seeing whether the FXO works properly in a fresh install.
My personal preference would be to fix or work around whatever required the SPA122 in the first place. Most providers don’t require registration to make calls, so a SIP trunk should work for outbound easily. There is also likely a way to receive calls without registration; who is your provider? If not, it should not be hard to determine why registration is intermittently failing (though it may not be easy to fix).