International imessaging, why doesn't my imessage say delivered?' will it be delivered?

My friend from the US has an iPhone and is in China on a business trip. He imessaged me (I'm in the US).

I was able to receive his iMessage. I have an iPhone ioS 7.1.1 through Verizon. I iMessedback back but it does not say "delivered". Why is this?

He told me he should be able to imessage me as long as he has Wi-Fi. Could this mean that he is not currently in an area with Wi-Fi ( hence no delivered status on the imessage I sent?).

When he does get to a Wi-Fi area will he receive my imessage then? (even if I sent my imessage about 3 hours before he gets to a Wi-Fi area?)

His imessage is from a gmail.com address if that helps. My imessage is my cell number.

Probably not in a Wi-Fi area. Once with reception his inbox should fill up. Best luck. Smart to use iMessage.