The IP telephone wave is coming

摘要

During the late 1970s and early 1980s, a wave of change swept across the enterprise telephone system industry, which was at that time referred to as the private branch exchange industry. The wave was caused by the technology shift from analog systems, which were the most common at the time, to digital TDM systems. These systems, which were smaller, less expensive to manufacture and simpler to maintain, became the focus of most PBX manufacturers.