The definition of customer success reps are members of an inside sales force that focus on customer retention. Their job is to make sure that customers are satisfied with products and services. It is also up to them to ensure that customers renew their contracts. customer success reps also often try to up-sell features to existing customers. Many companies have enjoyed success by separating inside sales teams into roles. Some other roles besides customer success reps include sales development reps (who handle outbound prospecting), marketing qualification reps (who handle inbound calls) and salespeople (who carry quotas and close deals.