show voice port - Tecnológico de Costa Rica

type
type
4-82
To specify the E&M interface type, use the type voice-port configuration command. Use the no form
of this command to reset the default value for this command.
type {1 | 2 | 3 | 5}
no type
Syntax Description
1 Indicates the following lead configuration:
E—output, relay to ground.
M—input, referenced to ground.
2 Indicates the following lead configuration:
E—output, relay to SG.
M—input, referenced to ground.
SB—feed for M, connected to -48V.
SG—return for E, galvanically isolated from ground.
3 Indicates the following lead configuration:
E—output, relay to ground.
M—input, referenced to ground.
SB—connected to -48V.
SG—connected to ground.
5 Indicates the following lead configuration:
E—output, relay to ground.
M—input, referenced to -48V.
Default
The default value is 1.
Command Mode
Voice-port configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.3(1)T.
Use the type command to specify the E&M interface for a particular voice port. With 1, the tie-line
equipment generates the E-signal to the PBX type grounding the E-lead. The tie line equipment
detects the M-signal by detecting current flow to ground. If you select 1, a common ground must
exist between the line equipment and the PBX.
With 2, the interface requires no common ground between the equipment, thereby avoiding ground
loop noise problems. The E-signal is generated toward the PBX by connecting it to SG. M-signal is
indicated by the PBX connecting it to SB. While Type 2 interfaces do not require a common ground,
they do have the tendency to inject noise into the audio paths because they are asymmetrical with
respect to the current flow between devices.
Voice over IP for the Cisco 3600 Series Software Configuration Guide