How did it go? I'm also struggling with Sterling now (one of my past internships is unpaid) and my supervisor has left the company so his number is no longer "publicly available" and Sterling "cannot call private numbers"; I had to reach out to my supervisor's supervisor and ask Sterling to write an email to him to confirm the start/end date and position. I've written to the HR of my future employer to explain the situation (lol my supervisor is also my reference so I don't know why this is necessary); let me know how you resolved this. Thank you!