What is one call? One Call is the industry’s leading provider of specialized solutions to the workers’ compensation industry.What is one call insurance? Summary. One Call is a Doncaster based insurance company, established in 1995. They offer a variety of insurance products, including car, van, home, travel and pet insurance. One Call did not make our list of the Top 10 Car Insurance Insurance Providers, but click the link to find out who did.What is one call center? A call center is an office where a company makes or receives a number of calls. It is also known as a customer support center, or tech support center. There are call centers that focus mostly on incoming (inbound), and mostly on outgoing (outbound) calls.