i think .its .i am using phone .or i am on phone

Likely this would be a slang expression by a younger person which means playing games on their phone. More correct, or natural to people who speak whole sentences might be I am playing mobile phone games. I am playing games on my mobile phone. I am playing games on my mobile. <-- more common, some places. I am playing games on my cell. I am playing games on my cellphone. I am playing games on my smartphone. . same for I am going to play .....

i think .its .i am using phone .or i am on phone

You use your phone to chat with your friends or look through the Internet

Can you provide some context?