T1/E1-Pbx Digital Voice Port Maximum Distances; Fxs Analog Voice Port Maximum Distance; Fxo Analog Voice Port Maximum Distance; Interference Considerations - Cisco IAD2430 Series Hardware Installation Manual

Interference Considerations

T1/E1-PBX Digital Voice Port Maximum Distances

Table 2-5
PBX.
Table 2-5
Signal Rate
T1/E1 (CSU)

FXS Analog Voice Port Maximum Distance

The maximum distance for a Foreign Exchange System (FXS) is established by a total allowable loop
resistance, including off-hook phone or terminal equipment, of 600 ohm. The maximum distance is
100 meters away from the system as a limitation of Ethernet.

FXO Analog Voice Port Maximum Distance

The maximum distance is determined by the distance between the PBX or other equipment that provides
battery and the connection to the FXO voice port.
Interference Considerations
When you run cables for any significant distance in an electromagnetic field, interference can occur
between the electromagnetic field and the signals on the cables. This has two implications for
installating terminal plant cabling:
•
•
If you use twisted-pair cables with a good distribution of grounding conductors in your plant cabling,
emitted radio interference is unlikely.
If you have cables that exceed the recommended distances, or if you have cables that pass between
buildings, give special consideration to the effect of lightning strikes or ground loops. If your site has
these characteristics, consult experts in lightning suppression and shielding. The electromagnetic pulse
caused by lightning or other high-energy phenomena can easily couple enough energy into unshielded
conductors to destroy electronic devices.
Without pulse meters and other special equipment, most data centers cannot resolve the infrequent but
potentially catastrophic problems just described. Take precautions to avoid these problems by providing
a properly grounded and shielded environment and by installing electrical surge suppression.
If you remove any module, you must either install a module in its place or install a cover plate over the
opening. All module openings must be either occupied or covered to prevent electromagnetic
interference.
For advice on the prevention of electromagnetic interference, consult experts in radio frequency
interference (RFI).
Cisco IAD2430 Series Integrated Access Devices Hardware Installation Guide
2-6
shows the maximum distances between the digital voice port of a Cisco IAD and a digital
Digital Voice Port Speed and Distance Limitations
Distance (Feet)
3000
Unshielded plant cabling can emit radio interference.
Strong electromagnetic interference (EMI), especially that caused by lightning or radio transmitters,
can destroy the EIA/TIA-232 drivers and receivers in the Cisco IAD.
Distance (Meters)
915
Chapter 2 Planning Your Installation
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