VoIP glossary · Private Branch Exchange
What is PBX?
A PBX (Private Branch Exchange) is a business phone system that connects internal extensions, handles features like queues and voicemail, and links the office to outside lines.
PBX explained
Modern PBXs are software, running on a server, a virtual machine or a dedicated appliance. Asterisk, FreePBX, 3CX, FusionPBX, Yeastar and Grandstream UCM are common examples. A SIP trunk replaces the old copper lines or PRI that once connected the PBX to the public network.
Whatever the platform, connecting a trunk follows the same pattern: set the server address and authentication, choose codecs, configure inbound and outbound routes, and sort out NAT. Our setup guides walk through each step for twelve platforms.
Example
A 40-person office runs FreePBX on a small server. Internal calls stay on the LAN, and outside calls go over a SIP trunk with 10 channels.
Put it into practice
Prepaid SIP trunks and wholesale routes from $200. Ask sales for rates or the NOC for a technical answer.