An EPABX system can control multiple incoming & outgoing voice calls at the same time. It is also used to have conference call within & outside the office. Further it can be divided into PRI & Analog lines. PRI means digital line with 100 calling extension (1:100) with the same number & analog is 1:1 line. Machine are available in some standard formats 3:8, 4:12, 4:16, etc. Intercom helps in doing free calling across the same network & also facilitates call conference.
