Responses
It’s a sound effect!
I think it's just a noise he's making with his mouth to show that he's been surprised/ taken aback. at least that's how I've been reading it as
Oh okay thank you!
What does UBT means? I've seen it several times in this story but I don't understand it... English isn't my mother tongue so I tried to find the meaning on the internet but the answers I found doesn't seem to fit the context