YOU SAID:

I couldn't answer the phone because I was on the toilet.

INTO JAPANESE

私はトイレにいたので電話に出られなかった。

BACK INTO ENGLISH

I could not answer the phone because I was in the toilet.

INTO JAPANESE

私はトイレにいたので電話に出られなかった。

BACK INTO ENGLISH

I could not answer the phone because I was in the toilet.