Hardware Installation Manual  22  Document #: LTRT-28030 
The FXS channel (port) number range of each FXS connector on an FXS blade is indicated 
by the labels (FXS 1-24, FXS 25-48, and FXS 49-72) located on the rear panel above the 
FXS blades, as shown below: 
Figure  3-8: FXS Blades and FXS Channels per FXS Connector (Rear Panel) 
 
 
The table below lists the specifications of the device's FXS ports.  
Table  3-9: FXS Port Specifications 
Specification  Description 
Analog Lifeline (PSTN 
Fallback) 
The FXS blade supports analog lifeline (PSTN Fallback). For 
more information, see Section  5.4 on page 41.  
Interface Type  FXS connection via 50-pin CHAMP connector 
FXS Signaling Formats  In-band signaling DTMF (TIA 464B) 
FXS Loop Impedance  Up to 1500 ohm (including phone impedance) 
Off-hook Loop Current 
  25 mA (maximum) on all ports 
  35 mA (maximum) on six ports per FXS Blade (for 
emergency / elevator phones) 
Ring Voltage (Sine) 
  54 Vrms 
  80 Vrms on six ports per FXS Blade (for emergency / 
elevator phones) 
Note:  
  Balanced ringing only. 
  Simultaneous ringing of 288 phones (72 per FXS Blade 
given REN 3 load) 
Ring Frequency  25-100 Hz 
Maximum Ringer Load  Ringer Equivalency Number (REN) 3 
Caller ID  Bellcore GR-30-CORE Type 1 using Bell 202 FSK 
modulation, ETSI Type 1, NTT, Denmark, India, Brazil, 
British and DTMF ETSI CID (ETS 300-659-1) 
Polarity Reversal / Wink  Immediate or smooth to prevent erroneous ringing