Call and hung up

Got three calls within one-half hour of one another from three 240 numbers: 240-857-6178, 240-857-6164, and 240-857-6168.  I didn't answer.  They left no message.  I'm tempted to answer the next one as this is annoying and I want to tell them to stop.  From what I've read here so far, it doesn't sound like I'll have much luck with that.

I get calls from 240-857-6164.  I never answer, but it leaves a message:  "If you are old enough to accept this call, please press the number 5."

It's Andrews AFB. Probably reminding you of a medical appt.

Yes medical reminder