Amazon Developer interview questions

Applied online for a software engineer position for new college graduates. Emailed a few recruiters using Linkedin to get my resume noticed. Received an email to setup a time and date for a phone interview. Phone interview was 45 minutes long, all technical. I will admit that this was my first technical phone interview, so my nerves got the best of me and I didn't answer the questions well. I was expecting conceptual questions instead I got coding questions. My interviewer was talking on a speakerphone and I had some trouble hearing/understanding him which didn't help. First question was something like, "Write a function that takes an integer and prints out the digits separated by commas. Example input 345, print out 3,4,5 " Second question was basically write the merge sort function and apply it to two arrays. Like I said before, this was my first technical phone interview so I was trying to figure out how to answer the questions over the phone. I described the method I would use to solve each problem, but he wanted me to tell him the actual code. Didn't go so well, and I didn't get an offer.