A European format for digital transmission. E1 supports signals at 2 Mbps (32 channels at 64Kbps, with 2 channels reserved for signaling and controlling), versus the T1, which carries signals at 1.544 Mbps (24 channels at 64Kbps).
“Call filter” allows blocking/unblocking the incoming calls as easy as to make filtration, it also journalizes all rejected calls. It is very convenient if you do not want to receive a call from some subscribers, when they will call you, “Call filter” will do so that your line is engaged.