ABSTRACT
Not too many years ago, there were basically two types of telephony switch es available, the Central Office and the PBX. The range of choice in features, prices and manufacturers was very limited and specialized switching needs were rarely addressed, if at all. The increasing demand for telecommunications has created the need for a wide range of specialized applications, including call back, 1+, international resale, cellular, paging, ACD, CLEC and many others.
