Often I find that many small businesses approach their office computer network like a low level home network, depending on residential grade gear and sometimes even wifi to connect workstations and key devices. Having the proper foundation in place will help you maximize performance and avoid unnecessary headaches.
First you need a hard wire cable connection to each location where you plan to have a computer, server, printer, or other device. All cable and components should be at minimum category 5e. Best practice is to have all cables wired to a central patch panel and to use appropriate wire management where needed. It is recommended to have at least two [Office cubes] cables terminated at each office work station, one for computer and one for phone or a secondary device. Most IP telephones can share a cable with a computer and most non-IP digital and analog telephones can run on lower cost category 3 cable, but if you are cabling from scratch, go with dual category 5e or higher connections. It is easier and lower cost to run the two cables together upfront than to retro-fit later. So you will need a patch cord from your computer/device to connect to a faceplate/jack terminated to the cable which is run to a common area where all cables are terminated to a patch panel. You will need patch cables to connect from patch panel to your switch gear. All cabling components should be certified to the same level, a minimum of category 5e, but category 6 will be a better choice for many networks.
Second you need a business grade router and a data switch. The router connects your office network to the Internet and/or other networks. A good router also provides firewall capability to block security threats and can give priority Internet access to selected computers or devices such as VoIP phones. Data switches connect computers and other devices such as servers and printers. This allows the devices to talk to each other and to share the common connection to the router and Internet. Depending on the coverage needed, Wifi may be added to the network through the router, wireless access points or a combination of the two.
I hope this is helpful, thank you for reading.