The difference between “hung up the phone” and “hang up the phone” relates to tense.
“Hung up the phone” is the past tense form, used to describe an action that has already occurred in the past. For example:
“After our conversation, she hung up the phone.”
“Hang up the phone” is the present/future tense form, used to describe an action that is currently happening or will happen. For example:
“I need to hang up the phone now.”
“Will you hang up the phone when you’re done?”
The past participle of “hang” is “hung” when referring to hanging objects like phones. So we say “hung up” in the past tense.
Sources that support this distinction:
- Grammarly clearly explains hung is the past tense of hang when hanging objects.
- Cambridge Dictionary defines the past tense as “hung” for hanging objects.
So in summary, “hung up the phone” refers to a past action, while “hang up the phone” is present/future tense.