A call centre or call center is a centralised office used for the purpose of receiving and transmitting a large volume of requests by telephone. A call centre is operated by a company to administer incoming product support or information inquiries from consumers. wikipedia.org

Order processing Order processing is a key element of Order fulfillment. Order processing operations or facilities are commonly called "distribution centers".

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.

Chat technical support is a form of technical support delivered via online chat. Online chat refers to a kind of communication over the Internet that offers an real-time direct transmission of text-based messages from sender to receiver. 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

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

Office administration is a set of day-to-day activities related to financial planning, billing and recordkeeping, personnel, and physical distribution and logistics, within an organization. wikipedia.org

Drop shipping is a supply chain management technique in which the retailer does not keep goods in stock, but instead transfers customer orders and shipment details to either the manufacturer or a wholesaler, who then ships the goods directly to the customer. wikipedia.org