I recently sent my friend in China an iMessage but it was sent as a text message instead. Will I be charged?

Short answer: Likely no with T-Mobile (Assuming T-Mobile USA)

T-Mobile's Current plans (assuming its not a very old grandfather plan, however I believe T-Mobile migrated everyone) come with free international texting to virtually every country in the world. Only a handful of countries are not included and they were obscure. (Not big like China)

So you should be fine 🙂

But to be 100% sure I make no guarantees call 611 from your device to get assistance (Again assuming T-Mobile USA)

Yes, I think so. There is an option under Messages called "send as SMS" which (when on) automatically sends an SMS when iMessage is unavailable.

Hi

The best people to ask are your mobile service provider

Ring them now from your iPhone .

Cheers

Brian uk