Specifications

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Cisco 1751 Router Software Configuration Guide
OL-1070-01
Example
The following example disables the icpif command:
dial-peer voice 10 voip
icpif 0
impedance
To specify the terminating impedance of a voice-port interface, use the impedance voice-port
configuration command. Use the no form of this command to restore the default value.
impedance {600c | 600r | 900c | complex1 | complex2}
no impedance
Syntax Description
Default
600 ohms.
Command Mode
Voice-port configuration.
Usage Guidelines
Use the impedance command to specify the terminating impedance of an FXO voice-port interface. The
impedance value selected needs to match the specifications from the specific telephony system to which
it is connected. Different countries often have different standards for impedance. CO switches in the
United States are predominantly 600r. PBXs in the United States are normally either 600r or 900c.
If the impedance is set incorrectly (if there is an impedance mismatch), a significant amount of echo is
generated (which could be masked if the echo-cancel command has been enabled). In addition, gains
might not work correctly if there is an impedance mismatch.
Configuring the impedance on a voice port changes the impedance on both voice ports of a VIC. This
voice port must be shut down and then opened for the new value to take effect.
This command applies to FXS, FXO, and E&M voice ports.
600c 600 ohms complex.
600r 600 ohms real.
900c 900 ohms complex.
complex1 Complex 1.
complex2 Complex 2.