Customer service is the provision of service to customers before, during and after a purchase. wikipedia.org

A data entry clerk, sometimes called a typist, is a member of staff employed to type data into a database using a keyboard. The keyboards used can often have specialist keys and multiple colours to help them in the task and speed up the work. wikipedia.org

Cold calling is the marketing process of approaching prospective customers or clients, typically via telephone, who were not expecting such an interaction. wikipedia.org

A sale is the act of selling a product or service in return for money or other compensation. It is an act of completion of a commercial activity. wikipedia.org

Telemarketing (sometimes known as inside sales, or telesales in the UK and Ireland) is a method of direct marketing in which a salesperson solicits prospective customers to buy products or services, either over the phone or through a subsequent face to face or Web conferencing appointment

Employee training and development are a function concerned with organizational activity aimed at bettering the job performance of individuals and groups in organizational settings. wikipedia.org

Phone technical support refers to a range of services by which enterprises provide assistance to users of technology products such as mobile phones, televisions, computers, software products or other electronic or mechanical goods via telephone.

A consumer complaint or customer complaint is an expression of dissatisfaction on a consumer's behalf to a responsible party. It can also be described in a positive sense as a report from a consumer providing documentation about a problem with a product or service. wikipedia.org

Retail consists of the sale of physical goods or merchandise from a fixed location, such as a department store, boutique or kiosk, or by mall, in small or individual lots for direct consumption by the purchaser. wikipedia.org

A collection agency is a business that pursues payments of debts owed by individuals or businesses. Most collection agencies operate as agents of creditors and collect debts for a fee or percentage of the total amount owed. wikipedia.org