Siting call centers in cheaper locations has been a norm in the US for years. If it couldn't be done that way, it would all have moved to India or the Philippines.

Most call center staff (non-technical) are easily and quickly trained on the job. There is also very high turnover in the industry, so quickly ramping up trained staff is part of basic operations. The recruits don't have to have any specialized skills other than being literate.

The CRM systems in place are also designed with a lot of call scripting in place to guide the conversations based on target companies and customers. Generally a single call center handles the customer service operations of multiple companies and teams of CSRS can be reconfigured to support different companies at different times.