Hi
Thanks for posting your question to the helpline.
You asked if there were any alternative phrases to "I beg your pardon." You could also say:
"Sorry; excuse me?"
"Sorry. What did you say"?
"Sorry. I didn't catch that."
"Sorry. Could you say that again?"
"Sorry. Could you repeat that?"
It's important to include the word "Sorry" in order to be polite.
Hope this answers your question.
Regards
The Helpline
Regards
Workplace English Training E-Magazine Team