IMessage not working in airplane mode?

I have an unlocked iPhone 4 on T-mobile. I turned on airplane mode and I turned on Wi-Fi. I tried to send a message through iMessage on my phone but it isn't sending. I'm trying to see if I can use iMessage when I travel to China for a trip for a month. The place I'm staying at for two weeks has no Wi-Fi and I'm wondering if there was a way to get internet for my phone!

Because airplane mode turns of all wireless connection. So turn it off.

Airplane mode turns off wireless and ability to text, call and all that on a air plane and if a flight attend see it she'll make you turn it off.

You have to find a place with Wi-Fi, like a coffee shop. Data will be expensive if you use that because you are roaming internationally.iMessage requires an internet connection (Wi-Fi or data plan) to use and it won't work in airplane mode unless you turn on Wi-Fi/connect to a Wi-Fi network. Airplane mode turns off all wireless signals, so iMessage isn't working because you have to connection at all.

Well, first of all your phone may or may not work in China at all. I, too, use T-Mobile. I travelled to China last summer.

In Kunming, i could text. I could make calls but not receive calls. In Shanghai, I could text but could not make calls. I could receive calls from some people. On the way to China, my phone did not work at all in Seoul and on the way home it did not work at all in Tokyo. To get it to work at all, I had to call T-Mobile before I left, too- you will need to select and activate a calling plan (no cost other than your usage).

EDITED TO ADD: You said you turned on Wi-Fi, but are you connected to a Wi-Fi source? If not, that is why the iMessage is not working. You have to be connected to Wi-Fi.
That said, my phone at the time was not a smart phone. I could access the internet from it but it did not have apps, etc. It was a world phone, which I believe the iPhone is as well. But with the iPhone you SHOULD be able to put it in airplane mode and still use features via Wi-Fi. I believe iMessage only works to message other iPhone users, though. Also, if where you are staying has no Wi-Fi then how will you use it over there? Confused on that.

Of course it's not working. The whole point of airplane mode is that it cuts off all connection with the outside world so you don't create interference with the airplane's electronics.

It IS possible to live without the Internet.