Multi-Tech Systems ISIHP-2S - Manual (Page 11)

MultiModemISI Hybrid Series, ISIHP-2S/2U 11
Hardware Installation
ISIHP-2U LED Indicators
P LED Indicator
• Indicates U interface status connection.
• Controlled by NT-1, which converts S/T interface
(4-wire ISDN) to U interface (2-wire ISDN).
• When U interface and S/T interface are NOT
active, LED remains off.
• Flashes 8 times/second (8 Hz)—U interface is
attempting to activate.
• Flashes once/second (1 Hz)—U interface is active;
S/T interface is not fully active.
• Lit, not flashing—Both U and S/T interfaces are
active.
D LED Indicator
• Lights when the ISIHP-2S/2U is turned on.
• Flashes until SPIDs are verified with the central
office switch; then remains lit without flashing.
• Indicates data link layer status.
LINE 2
P D
D
LINE 1
P