"i look forward to hearing from you" is an equivalent english translation of "looking forward to your callback"。
Source: this phrase is a common expression in english-language business e-mails and letter letters, which are used to express expectations for responses。
Example:
I look forward to hearing from you soon. I'm not sure
Please let me know if you have any questions, i look forward to hearing from you. I'm not sure
Thanks for your email, i look forward to hearing from you. I'm not sure
