Text messages sent internationally?

Could you please help me in the following?

1. I'm living in US and I sent text messages to a US person just traveling to China and Taiwan. I sent the messages using the same number that I used to call this person when he was in US.
Do you know if he will receive them in China/Taiwan please? ( I didn't add any international code in front of his iphone number)

2. If he can't receive them due to some reasons in China/Taiwan, will the message be sent to him after he comes back to US?

He's the one who doesn't like to get duplicate text messages, and he's been a bit mad at me recently. So I don't want to just keep sending messages, and I don't want to call him until later.

You could help me answer whatever you know.

I think I have answer on your another question. Actually, if he still using the number normally in China, he can receive your text message. Don't worry.