Preschool Conversations

Overheard while our 4 year old neighbour stood outside our gate...
"Hello" says Isabella.
Bryan replies, "Hello!"
"Hello"
"Hello" and both of them giggle.
"What are you doing out there?" Bryan asks.
Isabella replies with, "What are you doing down there?"
And followed by more giggles.

Then later in the evening, his 5 year old cousin calls up and specifically asks to speak to Bryan.
"Hello", Bryan pauses.
"Yes?"
"Wait... MOMMY! CAN I GO TO KATELYN JIE JIE'S HOUSE?"
To which I answer, "No. You have a cough."
Bryan disappears out of the room with the phone, then reappears minutes later only to pass me the phone. "Katelyn jie jie wants to speak to mommy."
And I end up having to explain politely over the phone to my 5 year old niece that Bryan has a cough. Maybe another day.

Since when has my 3 year old suddenly been able to hold a conversation over the phone? And with another preschooler too. And what in the world could they be talking about?