Inbound Telesales: Takes place when a potential customer/client calls the company inquiring about their products/services.
Inbound telesales is designed to cater to customer responses to the company's promotional/ advertising campaigns. Technical support executives also fall under this category if they do cross-sell.
Outbound Telesales: takes place when a telesales executive proactively initiates a call to a prospective customer. These calls can be for existing customers for cross-selling / up-selling new product/service offerings or for new customer acquisition.