First, Please keep in mind that your call blocker may not to be able to register all the incoming calls the same way your handset registers them mainly because they have different caller id reading software.
At times, a call blocker device is not able to register an incoming call mainly because it cannot validate the name or the phone number received from the calling party. Also, sneaky telemarketers may alter their call id information to prevent the call blockers from blocking them. In our experience, this happens very seldom and mostly on cell phone callers.
In essence, these calls are treated by your call blocker the same way it treats the UNKNOWN, PRIVATE, OUT OF AREA calls. You can turn feature # 6 to block these calls, however, this may also block legit calls. Please refer to this article for more details:
https://rentalo.freshdesk.com/solution/articles/5000626937-pros-cons-of-feature-set-6-blocking-calls-with-no-caller-id
Ref: https://www.hqtelecom.com/TLock-CallBlocker-Manual-V5.pdf
We hope this is helpful. Please feel free to contact us if you have more questions.
P.s, By the way, we are working on a new call blocking device that you allow you to block callers using their names. So, in this case you will be able to block all calls using a name regardless of the number number they use. Please register to receive our newsletters to learn more about this upcoming device.