Praise be to Allah.
If the woman is good in terms of religious commitment and character, and this young man definitely wants to propose to her, then there is nothing wrong with speaking to her over the phone, or meeting her in the presence of the mother or sister of the suitor, so long as they speak only as much as is necessary. Perhaps she wants to make sure about something, or to disclose something about herself so that the suitor will be fully informed. Once the desired purpose is achieved, then they must stop speaking, regardless of whether the proposal goes ahead or not.
And Allah knows best.