Lines And Trunks; Lines; Trunks - Mitel SX-2000 Light General Information Manual

• The system's tone generator supplies all audible tones (such as dial tone, busy tone, and
ringback tone) to the circuit switch for distribution to callers as required.
• At the Peripheral Interface card, voice signals from each telephone are converted into digital
form (pulse code modulation) and routed through the system on the established circuit;
signals leaving the switch are decoded back into analog form by the Peripheral Interface
card.

Lines and Trunks

Lines

The system supports the following types of internal voice lines:
• Digital Network Interface (DNI) Lines provide an interface for Mitel digital telephones,
consoles, and datasets. The maximum loop resistance on a DNI line must be 280 ohms or
less, and the loop length must be 3300 ft. (1000 m) or less on 26-gauge wire.
• These lines are supported by the Digital Network Interface line card.
• On-Premise (ONS) Lines (24 V per port) are for industry-standard rotary dial and DTMF
telephones. The external loop resistance on an ONS line must be 600 ohms or less, and
the loop length must be 5000 ft. (1500 m) or less on 26-gauge wire.
• These lines are supported by the ONS line card and the ONS CLASS/CLIP line card.
• Off-Premise (OPS) Lines (48 V per port) are for industry-standard telephones where the
external loop resistance exceeds 600 ohms or where lightning surge protection is required.
The maximum loop resistance on an OPS line must be 1800 ohms or less, and the loop
length must be 19,000 ft. (5800 m) or less on 26-gauge wire.
• These lines are supported by the OPS line card.
• Control Over Voice (COV) Lines provide an interface for voice mail systems. The maxi-
mum loop resistance on a COV line must be 280 ohms or less, and the loop length must
be 3300 ft. (1000 meters) or less on 26-gauge wire.

Trunks

The system can connect to the public switched network or to private networks over both digital
and analog trunks.
The following digital links are supported:
• DS1 Links: The system supports CO, DID, E&M, MSDN/DPNSS, and MSAN/APNSS
protocols.
• The SX-2000 LIGHT system connects to DS1 links by using a DS1 Formatter or DS1/T1
Formatter II card.
• CEPT Links: The system supports MSDN/DPNSS, DASS II (UK only), and Italian CAS
(Italy only) protocols.
Product Overview
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