Using virgin mobile phone carrier in the US to send text messages to south korea?

Why doesn’t my phone let me send text messages to my boyfriend in Korea? His phone carrier is SK Telecom and I have virgin mobile. I had the same problem with Boost Mobile, it wouldn’t let me send text messages but I can receive his.
I’ve tried the 011 82 10… and 8210 and 011 82 010 and no luck.
When I had AT&T I could recieve and text but virgin and boostmobile won’t let me.
Any suggestions?

yea virgin mobile sucks!
change your phone carrier

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