The best way to learn proper English is to read news report, and watch news on TV. Watching TV shows is a great way to learn casual English, slang words, understand culture reference and humor. If you have already watched these shows then you may recall the words used in the following dialogs.

We have another CALLER.
Hi, you're on Fun with Flags.
The Big Bang Theory Season 9, Episode 15

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

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

All right, we have our next CALLER.
The Big Bang Theory Season 10, Episode 21

Hello, CALLER. You are on with Penny and Wil
from Serial Ape-ist 2.
The Big Bang Theory Season 8, Episode 20