1. I promised to call back within an hour.
2. I promised to call back in an hour.
The two sentences have different meanings.
Let's say you made the promise at 10.00.
'Call back within an hour' means you will call back anytime between 10.00 and 11.00.
'Call back in an hour' means you will call back at 11.00.
not a teacher
I promised to call back within an hour.
I saw this expression. How about following?
I promised to call back in an hour.
Yes, that's right, tedtmc's answer is correct.Neither sound strange, but they have a bit different meaning, right?
Thank you!