Nothing was said

phone rang I picked it up 3rd ring, nothing, call just ended

ive answered and nothing happens. screen says call ended

got a call three times from this number. pick up and call ends. called back and got a verizon message that this number has been disconnected. did a reverse lookup online and got a linden al recall. no name. got another call this morning from 815-587-5227 with the same thing. no message. pick up and call is gone. called back and got a verizon message that said was disconnected. this one came back as in ottawa il. what is going on?