In 1995, Özçalkan started a group called U.C.S, and performed with this group until about 1998. His group Nefret got signed under Hammer Music in 2000, and the album "Meclis Ala – İstanbul" was released. In 2001, Özçalkan proceeded to release the album "Anahtar". The title track on this album that holds the same name as the album itself was the first one that came with a music video. The album was a great success, and Özçalkan got to give many concerts with it.