I know that point, I just say that it have drop the registration, showing "-" and that I had have to restart it.
Now, after "Pending", and waiting has usual, I have again a "-" in place of "registered" or "failed", which is unexpected. But, I have then tried to call myself with my GSM, and my phone has ring, which means that I am registered !
So status shown is not real status ! Thats better than last week, where status were failed and nothing work, but I am now worried on the stability of your solution. It has work perfectly for month, and now seems unreliable