A PBX (private branch exchange) system for small business is a phone system that connects your office phones to the public switch telephone network (PSTN). The small business PBX manages incoming and outgoing calls, both from internal extensions and external numbers. A PBX impacts almost every aspect of your business, including your budget, employee productivity, and customer care. Without a PBX system, your business is left with no ability to direct calls to specific departments or employees. An outside call will ring every phone, and there are no extensions enabling one-on-one calling within the office.