We all turn a little grey once we reach a certain age. The same goes for our hearing.
Sorry, I couldn't resist!
The only way I could see moving affecting it is if your VoIP provider whitelisted an IP range. Who is the VoIP provider? Can you verify the extension status on their website? You should also be able to reset the password on their site, and update it in Zoiper to match.
It sounds like Zoiper keeps trying to register with your provider and failing.