Based on what we have been able to troubleshoot, this is due to noise on the line generated by the local phone services. We have seen this issue in some VOIP services. Below are some suggestions on how to work around this issue: The following are possible fixes that have helped other clients reduce the amount of random digits and display freezes:
1) Install a ‘DSL filter” between the Vonage modem and your Call
Blocker, using the ‘Voice” jack of the modem to connect to the Blocker.
2) Other clients have been able to regain control of the unit by simply unplug the blocker for 1-2 minutes.
3) Other clients wait for an incoming call to re-gain control of the unit.
4) Other clients request an exchange for our new Landline Call Blocker model which has its own power supply and batteries -- (We will apply full credit for the price you paid, just pay the difference between what you paid for your call blocker and this model, and return the original unit to us).
Related Article: http://help.hqtelecom.com/solution/articles/5000004525-my-display-is-getting-freeze-frozen-e-g-none-of-the-buttons-work-and-or-getting-random-digits-