It all depends. After I lost my job as a part-time telephone agent in July, the call center that I worked in closed. There were heavy rains and thunderstorms here in the Philadelphia on Sunday, August 2. The company was located in a flood-prone area and two inches of water got into the building; damaging the call center. That Thursday (August 6), my coworker called and said that they decided to close the call center. When Tropical Storm Allison hit here in 2001, three feet of water got into the building, and they had to conduct business in the parking lot.
Also, back in the late 80's, I had worked at a medical telemarketing firm. After working there for 14 months, the company's Vice President of Sales came into our office and told us that they were closing the call center because the building's management decided not to renew their lease; and we all lost our jobs. We had worked out of a branch office, and the main office was not accesible by public transportation. To me, this was a sudden decision. I didn't know that they were delaying projects and laying people off.
Although it's sad but true, companies have the right to close up their call centers, and without warning. If that ever happens, you can always file for unemployment.