Alison has performed with New York City Opera (Bess in Porgy & Bess and Elvira in Don Giovanni), Opera company of Philadelphia, Michigan Opera, and Wexford Opera, she has performed under the batons of Sir. Simon Rattle, Sir. Colin Davis, Donald Runnicles, and David Agler to name but a few, with orchestra’s such as the Royal Philharmonic, the Philippines Philharmonic, the London Symphony, the Jacksonville Symphony, the BBC Symphony Orchestra and the Israel Kibbutz Orchestra.

Mr. Sims has been highly praised for his moving interpretations of African American spirituals, and has given numerous recitals of them throughout the United States, Europe, Africa and Asia. He has appeared with many orchestras in the U.S., and toured Japan with the Pacific Music Festival Orchestra where he was featured in a nationally televised performance of Bernstein's Opening Prayer. In 2005, Sims made his recital debut at Carnegie Hall and was invited by Jessye Norman to participate in Honor!