If I don't tell you, you can ask on the phone or on your first day.
If you leave your job and want to compare your current salary to decide whether to leave, you can consult your salary. After all, job-hopping is a big deal, which affects your work and life. The big deal is that HR is unhappy and won't let you join the job, so you will continue to work in your current position.
If you leave, you can ask by phone, or on the first day of employment, or you need this job very much, and you can accept it regardless of the salary, or you can not ask for it for the time being. You can also find an opportunity to ask when HR handles the entry formalities for you and familiarizes you with the company.