YOU SAID:

I wrote this sentence while on my phone

INTO JAPANESE

私は自分の携帯電話の中にこの文を書いた

BACK INTO ENGLISH

I wrote this sentence in my phone

INTO JAPANESE

自分の携帯電話でこの文を書いた

BACK INTO ENGLISH

Wrote this on my mobile phone

INTO JAPANESE

私の携帯電話にこれを書いた

BACK INTO ENGLISH

Wrote this on my mobile phone