The main reason why the UBlocker stops registering calls is because it looses its network connectivity.  There are a number of reasons why this may happen, but they are all related to your local network.  Below are some tips to prevent these network issues:

1) If possible, assign a permanent IP to your UBlocker on your router.  This will require for you to make changes to your DHCP server settings.

2) Try setting up your UBlocker with a static IP on an external network e.g. DMZ or IP Passthrough.

3) Setup a local PC or labtop to ping your UBlocker frequently so it it will not loose its connection to the router.  

4) If you have a WIFI UBlocker, you may want to replace it with a LAN version.  Just contact us for details.