Why does he say "it's Ross" with using "it's" not "I'm"? Is it a rule in phone call situation?
"It's Ross" is short for "it's Ross speaking". This is a common way to start a conversation with someone over the phone who you already know. "I'm" is used to introduce yourself to someone you don't know, so if he was calling someone he didn't know, he could say "Hi, I'm Ross" or "Hi, my name is Ross". With caller ID these days, it might not be necessary to identify yourself when calling someone who already has your name and phone number saved in their phone.
Get more Native English Expressions >