Mini pabx Capacity: Basic 4 CO lines, 8 extensions (408),expand ... , 424,432,832,896,1288,1696,1680 Transfer caller ID Mini pabxCapacity: Basic 4 CO lines, 8 extensions (408), expand to ... , 432, 832, 896, 1288, 1696, 1680 Main Features:Switch powerBackup battery interfaceBilling software (optional)Reverse polarity signal (optional)Transfer caller ID ...