I have a panasonic, you have to look thru manual, but the commands for mine are menu #217, can block up to 30 numbers and menu #240 blocks all calls that do not display a phone number.
Caller ID listed it as Teliax, Inc. They refused to give me any information on who they were until I gave my own name and contact info. I refused to give my own name since they would not say who they were. Sounds like an identity fraud scheme.
Called the woman said she was from Senior Services with a survey, she wanted my name, birthday and address. I am not nice to unwanted calls so I asked first for her name, address and birthday along with her company facts she hung up on me. It came up as a private caller on my caller ID so I knew it was a scam.