The dictionary says
hang up phrasal verb
1 to finish a telephone conversation
I said goodbye and hung up.
Don’t hang up on me.
Does "hang up on somebody" imply the conversation has not finished yet?
Normally, "we hang up the phone" after we say goodbye to the person we talk on the phone.
Does "she hung up on me" mean she hung up the phone before the conversation finished maybe she got upset with me or maybe her phone reception was bad so she pressed the "End Call" button or some other reasons?