StarTek Inc., a call center, will cease operations and lay off its 454 employees at the end of the year. The customer-service facility will stop its Petersburg operations on December 27, a letter sent to the Virginia Employment Commission said. The facility on South Crater Road first opened in Petersburg in 2006. It closed once before, in January of last year, but re-opened in the summer of 2007 after getting a new client, a wireless provider StarTek wouldn’t name.