This number, 202-567-5767, called my mobile phone and left a voicemail. It was an auto-dialer for the Human Rights Campaign (HRC) rallying constituents to contact their legislators in Washington, DC today as the new Equality Bill, which will end workplace, housing, and other types of shameful discrimination against LGBTQ citizens illegal in all 50, has been introduced in the Capitol and will be coming up for a vote soon.
I have an Android phone and use an app called PhoneWarrior.It lets you block numbers. For my home phone, I use Ooma. It lets you block up to 256 callers.
On the iPhone in the phone call registry, there is an i in a circle to the right of the number. I click on that and scroll down to the option, Block This Caller. When I tap on that, the number is blocked forever.