
Unknown CALLER.
It's got to be them.
The Big Bang Theory Season 12, Episode 23

It's time for a very special guest CALLER.
The Big Bang Theory Season 8, Episode 20

Need the location of an incoming CALLER.
Breaking Bad Season 5, Episode 14

...there is a gentleman CALLER
bringing flowers to your fiancée as we speak.
The Big Bang Theory Season 8, Episode 7

You know what?
That's not a flag question, next CALLER.
The Big Bang Theory Season 9, Episode 15