|
|
This document describes the advanced voice busyout (AVBO) feature introduced in Cisco IOS Release 12.1(3)T, which expands the local voice busyout feature on the Cisco 2600 and 3600 series routers and Cisco MC3810 series concentrators.
This document includes the following sections:
The local voice busyout feature provides a way to busy out a voice port or DS0 group (timeslot) if a state change is detected in a monitored network interface (or interfaces). When a monitored interface changes to a specified state—to out-of-service or in-service —the voice port presents a seized/busyout condition to the attached PBX or other customer premises equipment (CPE). The PBX or other CPE can then attempt to select an alternate route.
AVBO adds the following functionality to the local voice busyout feature:
Local voice busyout is supported on analog and digital voice ports using channel associated signaling (CAS).
The AVBO feature allows you to perform the following tasks:
RTR probe monitoring of remote interfaces is intended for use with VoIP networks, although it can also be used with Voice over Frame Relay (VoFR) and Voice over ATM (VoATM) networks.
These enhancements to the local voice busyout feature provide the following benefits:
The following restrictions and limitations apply to RTR probe monitoring of remote interfaces:
The AVBO feature is an enhancement to the local voice busyout feature, which is documented in the Cisco IOS Multiservice Applications Configuration Guide and the Cisco IOS Multiservice Applications Command Reference.
Configuration of the voice port to use an RTR probe to monitor the link to the remote interface is related to the RTR probe/responder features, which are documented in the Cisco IOS Multiservice Applications Configuration Guide and the Cisco IOS Multiservice Applications Command Reference.
The RTR probe feature is related to the PSTN fallback feature, which is documented in the Cisco IOS Multiservice Applications Configuration Guide and the Cisco IOS Multiservice Applications Command Reference.
PSTN Fallback, Cisco IOS Release 12.1(3)T feature module
Cisco IOS Multiservice Applications Configuration Guide, Cisco IOS Release 12.1
Cisco IOS Multiservice Applications Command Reference, Cisco IOS Release 12.1
This feature is supported on the following Cisco platforms:
Standards
ITU-T G.113 General Characteristics of International Telephone Connections and International Telephone Circuits
You should complete the following configuration tasks before configuring the RTR probe feature:
If the RTR probe feature is to be implemented, you must configure the following:
Complete the following task to configure a voice port to enter the busyout state if an RTR probe signal returned from a remote, IP-addressable interface crosses a specified delay or loss threshold:
Complete the following task to define a voice class with specified busyout conditions, and assign a particular voice class to any number of voice ports:
Complete the following task to assign a voice class to a voice port:
You can configure voice ports individually for busyout, or you can apply a voice class that includes all of the busyout parameters (see the "Configuring a Voice Class for Local Voice Busyout" section and the "Assigning a Voice Class to a Voice Port" section).
 |
Note If you have already assigned a busyout voice class to a voice port, you cannot configure busyout using this procedure; the command will be rejected. |
To configure a voice port to go into the busyout state when the RTR probe signal returned from a remote interface crosses a predetermined threshold, complete the following steps beginning in global configuration mode:
| Command | Purpose | |||
|---|---|---|---|---|
Step 1 | For Cisco 2600 and 3600 series analog voice ports: router(config)# voice-port slot/subunit/port For Cisco 2600 and 3600 series digital voice ports: router(config)# voice-port slot/port:ds0-group
For Cisco MC3810 series analog voice ports: router(config)# voice-port slot/port
For Cisco MC3810 series digital voice ports: router(config)# voice-port slot:ds0-group | Identify the voice port you want to configure and enter voice-port configuration mode. | ||
Step 2 | router(config-voiceport)# busyout monitor probe | Configure the voice port to use an RTR probe to monitor the link to the remote interface identified by an IP address. To configure the voice port to monitor multiple remote interfaces, reenter the command for each additional interface to be monitored. Optionally specify a codec profile for the RTR probe signal. Optionally specify a calculated planning impairment factor (ICPIF) loss/delay threshold, or specify loss and delay thresholds individually. Packet loss and delay determine the threshold for initiating the busyout state. If you do not enter threshold values, the threshold values for packet delay from the pstn fallback command are used.
If you configure a voice port to monitor multiple links, busyout occurs only when all of the monitored links go below the threshold. | ||
Step 3 | router(config-voiceport)# exit | Exit from the voice port configuration mode. |
Complete the following tasks to verify that a voice port is correctly configured to monitor the link to a remote interface:
Step 2 Enter the show voice busyout command to display information about the busyout state.
The following is a sample display from the show voice busyout command for voice ports on a Cisco MC3810:
router# show voice busyout Voice port busyout will be triggered by the
following network interfaces states
1/1 probe 209.165.202.128 codec g711u icpif 25
1/2 probe 209.165.202.128 codec g711u icpif 25
1/3 probe 209.165.202.128 codec g711u icpif 25
The following voice ports are in busyout state
1/1 is in busyout state caused by
probe 209.165.202.128 codec g711u icpif 2 1/2 is in busyout state caused by
probe 209.165.202.128 codec g711u icpif 2 1/3 is in busyout state caused by
probe 209.165.202.128 codec g711u icpif 2
A busyout voice class can provide for monitoring local ports (serial and Ethernet) and links to remote IP addresses. Busyout occurs when all of the monitored local ports are out of service or when all of the monitored links go below the threshold.
To define a voice class with specified busyout conditions, complete the following steps beginning in global configuration mode:
| Command | Purpose | |||
|---|---|---|---|---|
Step 1 | router(config)# voice class busyout tag | Create a voice class for defining busyout conditions. The range for the tag number is 1 to 10000. The tag number must be unique on the router. | ||
Step 2 | router(config-voice-class)# busyout monitor serial | (Optional) Specify a local serial interface to be monitored by the voice port(s). To configure the voice port(s) to monitor multiple interfaces, reenter the command for each additional interface to be monitored. The default is to busyout the voice port(s) when the monitored interface goes out of service. Enter the keyword in-service to configure the voice port(s) for busyout when the monitored interface comes into service. If you configure a voice port to monitor multiple interfaces for out-of-service states, busyout occurs only when all of the monitored serial and Ethernet interfaces go out of service. If you configure a voice port to monitor multiple interfaces for the in-service state, busyout occurs when any one monitored serial or Ethernet interface comes into service. | ||
Step 3 | router(config-voice-class)# busyout monitor ethernet | (Optional) Specify a local Ethernet interface to be monitored by the voice port(s). To configure the voice port(s) to monitor multiple interfaces, reenter the command for each additional interface to be monitored. The default is to busyout the voice port(s) when the monitored interface goes out of service. Enter the keyword in-service to configure the voice port(s) for busyout when the monitored interface comes into service. If you configure a voice port to monitor multiple interfaces for out-of-service states, busyout occurs only when all of the monitored serial and Ethernet interfaces go out of service. If you configure a voice port to monitor multiple interfaces for the in-service state, busyout occurs when any one monitored serial or Ethernet interface comes into service. | ||
Step 4 | router(config-voice-class)# busyout monitor probe | (Optional) Configure the voice port to use an RTR probe to monitor the link to the remote interface identified by an IP address. To configure the voice port to monitor multiple remote interfaces, reenter the command for each additional interface to be monitored. Optionally specify a codec profile for the RTR probe signal. Optionally specify a calculated planning impairment factor (ICPIF) loss/delay threshold, or specify loss and delay thresholds individually. Packet loss and delay determine the threshold for initiating the busyout state. If you do not enter threshold values, the threshold values for packet delay from the pstn fallback command are used.
If you configure a voice port to monitor multiple links, busyout occurs only when all of the monitored links go below the threshold. | ||
Step 5 | router(config-voice-class)# exit | Exit from the voice-class configuration mode. |
After you have created the voice class for busyout function, assign it to all of the voice ports that have these busyout requirements. See the "Assigning a Voice Class to a Voice Port" section.
Assign the voice class to a voice port as described in the "Assigning a Voice Class to a Voice Port" section, and verify the busyout function of the voice port.
To assign a particular voice class to a voice port, complete the following steps beginning in global configuration mode:
| Command | Purpose | |||||
|---|---|---|---|---|---|---|
Step 1 | For Cisco 2600 and 3600 series analog voice ports: router(config)# voice-port slot/subunit/port For Cisco 2600 and 3600 series digital voice ports: router(config)# voice-port slot/port:ds0-group
For Cisco MC3810 series analog voice ports: router(config)# voice-port slot/port
For Cisco MC3810 series digital voice ports: router(config)# voice-port slot:ds0-group | Identify the voice port you want to configure and enter voice-port configuration mode. | ||||
Step 2 | router(config-voiceport)# voice class busyout tag | Assign a busyout voice class to this voice port. You will very likely assign the same busyout voice class to multiple voice ports.
| ||||
Step 3 | router(config-voiceport)# exit | Exit from the voiceport configuration mode. |
Repeat the above procedure for each voice port to be configured for busyout.
Complete the following tasks to verify that a voice port is correctly configured for busyout monitoring:
|
Note Be sure that call fallback is configured on the local router and RTR responder is configured on the target router. |
Step 2 Enter the show voice busyout command to display information about the busyout state.
The following is a sample display from the show voice busyout command for voice ports on a Cisco MC3810:
router# show voice busyout Voice port busyout will be triggered by the
following network interfaces states
1/2 busyout monitor ATM0
1/3 busyout monitor ATM0
1/4 busyout monitor Serial0
1/5 busyout monitor Serial0
1/6 probe 209.165.202.128 codec g711u icpif 25
The following voice ports are in busyout state
1/1 is forced into busyout state
1/2 is in busyout state caused by ATM0
1/3 is in busyout state caused by ATM0
1/4 is in busyout state caused by Serial0
1/5 is in busyout state caused by Serial0 1/6 is in busyout state caused by
probe 209.165.202.128 codec g711u icpif 2
The following example configures busyout voice class 30, which initiates voice-port busyout whenever serial ports 0 and 1 both go out of service, and it applies voice class 30 to voice port 1/3:
router(config)# voice class busyout 30 router(config-voice-class)# busyout monitor serial 0 router(config-voice-class)# busyout monitor serial 1 router(config-voice-class)# exit router(config)# voice-port 1/3 router(config-voiceport)# voice class 30
The following example configures busyout voice class 35, which initiates voice-port busyout whenever either serial port 0 or 1 is in service, and it applies voice class 35 to voice port 1/3:
router(config)# voice class busyout 35 router(config-voice-class)# busyout monitor serial 0 in-service router(config-voice-class)# busyout monitor serial 1 in-service router(config-voice-class)# exit router(config)# voice-port 1/3 router(config-voiceport)# voice class 35
The following example configures busyout voice class 40, which initiates voice-port busyout whenever an RTR probe sent to both of the two specified remote interfaces results in a link with an ICPIF delay/loss average of more than 15, and it applies voice class 40 to voice port 1/4:
router(config)# voice class busyout 40 router(config-voice-class)# busyout monitor probe 209.165.202.128 icpif 15 router(config-voice-class)# busyout monitor probe 209.165.202.129 icpif 15 router(config-voice-class)# exit router(config)# voice-port 1/4 router(config-voiceport)# voice class 40
The following example configures analog voice port 1/1 on a Cisco MC3810 to use an RTR probe with a G.711 alaw profile to probe the link to the remote interface with IP address 209.165.202.128, and to busyout the voice port if the link has a packet loss of more than 50 percent and a packet delay of more than 25 milliseconds:
router(config)# voice-port 1/1 router(config-voiceport)# busyout monitor probe 209.165.202.128 codec g711a loss 50 delay 25
The following example configures voice port 1/0/1 on a Cisco 3600 series router to use an RTR probe with the default (G.711 ulaw) profile to probe the link to the remote interface with IP address 209.165.202.128, and to busyout the voice port if the link has packet loss and delay that exceed the threshold values configured by the pstn fallback command:
router(config)# voice-port 1/0/1 router(config-voiceport)# busyout monitor probe 209.165.202.128
The following example configures busyout voice class 60, which configures multiple parameters for voice-port busyout, and it applies voice class 60 to voice ports 1/0/0 and 1/0/1 on a Cisco 3600 series router. The voice ports will busy out under any one the following conditions:
router(config)# voice class busyout 60 router(config-voice-class)# busyout monitor serial 0/0 router(config-voice-class)# busyout monitor serial 0/1 router(config-voice-class)# busyout monitor serial 1/0 in-service router(config-voice-class)# busyout monitor serial 1/1 in-service router(config-voice-class)# busyout monitor probe 209.165.202.128 loss 50 delay 1000 router(config-voice-class)# busyout monitor probe 209.165.202.129 loss 50 delay 1000 router(config-voice-class)# exit router(config)# voice-port 1/0/0 router(config-voiceport)# voice class 60 router(config-voiceport)# exit router(config)# voice-port 1/0/1 router(config-voiceport)# voice class 60 router(config-voiceport)# exit
The following new and modified commands are described in this section (modified commands are marked by an asterisk):
To configure a voice port to monitor a local Ethernet interface for events that would trigger a voice-port busyout, use the busyout monitor ethernet voice-port configuration command. To configure a voice port not to monitor an Ethernet interface for such events, use the no form of this command
busyout monitor ethernet interface-number [in-service]Syntax Description
interface-number | Identifies an Ethernet interface to be monitored for the voice-port busyout function. |
in-service | (Optional) Configures the voice port to be busied out when any one monitored interface comes into service (state changes to up). If the keyword is not entered, the voice port is busied out when all monitored interfaces go out of service (state changes to down). |
Defaults
The voice port does not monitor any interfaces.
Command Modes
Voice-port configuration.
Command History
| Release | Modification |
|---|---|
12.0(3)T | This command was introduced on the Cisco MC3810 series. |
12.0(7)XK | This command was first supported on the Cisco 2600 and 3600 series, and the ability to monitor an Ethernet port was introduced. |
12.1(3)T | The keyword interface was removed. |
Usage Guidelines
A voice port can monitor multiple interfaces at the same time. To configure a voice port to monitor multiple interfaces, reenter the busyout monitor ethernet command for each additional interface to be monitored.
You can combine in-service and out-of-service monitoring on a voice port. The following rule describes the actions if monitored interfaces change state:
A voice port is busied out if:
Examples
The following example configures voice port 2/1 on a Cisco 3600 series router to busyout if Ethernet ports 0/0 and 1/0 both go out of service:
router(config)# voice-port 2/1 router(config-voiceport)# busyout monitor ethernet 0/0 router(config-voiceport)# busyout monitor ethernet 1/0 router(config-voiceport)#
The following example configures digital voice port 0:6 on a Cisco MC3810 to busyout if both Ethernet port 0 and serial port 0 go out of service:
router(config)# voice-port 0:6 router(config-voiceport)# busyout monitor ethernet 0 router(config-voiceport)# busyout monitor serial 0 router(config-voiceport)#
The following example configures digital voice port 0:1 on a Cisco MC3810 to busyout if Ethernet port 0 comes into of service:
router(config)# voice-port 0:1 router(config-voiceport)# busyout monitor ethernet 0 in-service router(config-voiceport)#
Related Commands Related Commands
| Command | Description |
busyout forced | Forces a voice port into the busyout state. |
Configures a voice port to enter the busyout state if an RTR probe signal returned from a remote, IP-addressable interface crosses a specified delay or loss threshold. | |
Configures a voice port to monitor a serial interface for events that would trigger a voice-port busyout. | |
busyout seize | Changes the busyout seize procedure for a voice port. |
show voice busyout | Displays information about the voice busyout state. |
To configure a voice port to enter the busyout state if an RTR probe signal returned from a remote, IP-addressable interface crosses a specified delay or loss threshold, use the busyout monitor probe voice-port configuration command. To configure a voice port not to monitor RTR probe signals, use the no form of this command.
busyout monitor probe ip-address [codec codec-type] [icpif number | loss percent delay milliseconds]Syntax Description
ip-address | The IP address of a target interface for the RTR probe signal. |
codec | (Optional) Configures the profile of the RTR probe signal to mimic the packet size and interval of a specific codec type. |
codec-type | (Optional) The codec type for the RTR probe signal. Available options are:
|
icpif | (Optional) Configures the busyout monitor probe to use a Calculated Planning Impairment Factor (ICPIF) loss/delay busyout threshold, in accordance with ITU-T G.113. The ICPIF numbers represent predefined combinations of loss and delay. |
number | (Optional) The ICPIF threshold for initiating a busyout. The range is 0 to 30. Lower numbers are equivalent to lower loss and delay thresholds. |
loss | (Optional) Configures the percent of packets lost threshold for initiating a busyout. |
percent | (Optional) The loss value in percent for initiating a busyout. The range is 1 to 100. |
delay | (Optional) Configures the average packet delay threshold for initiating a busyout. |
milliseconds | (Optional) The delay threshold in milliseconds for initiating a busyout. The range is 1 to 2147483647. |
Defaults
If the busyout monitor probe command is not entered, the voice port does not monitor RTR probe signals.
If the busyout monitor probe command is entered with no optional keywords or arguments, the default codec type is G.711 alaw and the default loss and delay thresholds are the threshold values configured with the pstn fallback command.
Command Modes
Voice-port configuration.
Command History
| Release | Modification |
|---|---|
12.1(3)T | This command was introduced on the Cisco 2600, 3600, and MC3810 series. |
Usage Guidelines
A voice port can monitor multiple interfaces at the same time. To configure a voice port to monitor multiple interfaces, reenter the busyout monitor probe command for each additional interface to be monitored.
The busyout monitor probe command is effective only if the call fallback function is enabled on this router and the RTR responder is enabled on the target router.
The RTR probe is transmitted periodically with a period determined by the call fallback function.
Refer to the PSTN Fallback feature module for Cisco IOS Release 12.1(3)T for details of the call fallback function and ICPIF values.
Lower thresholds of ICPIF, loss, and delay result in earlier busyout when the link deteriorates, thereby raising the voice minimum quality level. Higher thresholds prevent busyout until loss and delay are greater, allowing transmission of lower-quality voice.
 |
Caution If thresholds are set too low, the link can alternate between in-service and out-of-service states, causing repeated interruptions of traffic. |
Examples
The following example configures analog voice port 1/1 on a Cisco MC3810 to use an RTR probe with a G.711alaw profile to probe the link to two remote interfaces with IP addresses, and to busyout the voice port both links have a loss exceeding 25 percent or a packet delay of more than 1.5 seconds:
router(config)# voice-port 1/1 router(config-voiceport)# busyout monitor probe 209.165.202.128 codec g711a loss 25 delay 1500 router(config-voiceport)# busyout monitor probe 209.165.202.129 codec g711a loss 25 delay 1500 router(config-voiceport)#
Related Commands Related Commands
| Command | Description |
Configures a voice port to monitor a local Ethernet interface for events that would trigger a voice-port busyout. | |
Configures a voice port to monitor a serial interface for events that would trigger a voice-port busyout. | |
pstn fallback | Forces a voice port into the busyout state. |
show voice busyout | Displays information about the voice busyout state. |
Creates a voice class for local voice busyout functions. |
To configure a voice port to monitor a serial interface for events that would trigger a voice-port busyout, use the busyout monitor serial voice-port configuration command. To configure a voice port not to monitor a serial interface for such events, use the no form of this command
busyout monitor serial interface-number [in-service]Syntax Description
serial | Specifies monitoring of a serial interface.
| ||
interface-number | Identifies an interface to be monitored for the voice-port busyout function. Interface choices can include both serial ports and serial port subinterfaces. | ||
in-service | (Optional) Configures the voice port to be busied out when any one monitored interface comes into service (state changes to up). If the keyword is not entered, the voice port is busied out when all monitored interfaces go out of service (state changes to down). |
Defaults
The voice port does not monitor any interfaces.
Command Modes
Voice-port configuration.
Command History
| Release | Modification |
|---|---|
12.0(3)T | This command was introduced on the Cisco MC3810 series. |
12.0(7)XK | This command was first supported on the Cisco 2600 and 3600 series. |
12.1(3)T | The keyword interface was removed. |
Usage Guidelines
A voice port can monitor multiple interfaces at the same time. To configure a voice port to monitor multiple interfaces, reenter the busyout monitor serial command for each additional interface to be monitored.
You can combine in-service and out-of-service monitoring on a voice port. The following rule describes the actions if monitored interfaces change state:
A voice port is busied out if:
Examples
The following example configures analog voice port 1/1 on a Cisco MC3810 to busyout if serial ports 1 and 0:0 both go out of service:
router(config)# voice-port 1/1 router(config-voiceport)# busyout monitor serial 0:0 router(config-voiceport)# busyout monitor serial 1 router(config-voiceport)#
The following example configures analog voice port 1/2 on a Cisco MC3810 to busyout if serial port 0 or 1 comes into service:
router(config)# voice-port 1/2 router(config-voiceport)# busyout monitor serial 0 in-service router(config-voiceport)# busyout monitor serial 1 in-service router(config-voiceport)#
The following example configures digital voice port 1/2:2 on a Cisco 3600 series router to busyout if serial ports 0/0, 0/1, 1/0 and 1/1 all go out of service:
router(config)# voice-port 1/2:2 router(config-voiceport)# busyout monitor serial 0/0 router(config-voiceport)# busyout monitor serial 0/1 router(config-voiceport)# busyout monitor serial 1/0 router(config-voiceport)# busyout monitor serial 1/1 router(config-voiceport)#
The following example configures digital voice port 0:6 on a Cisco MC3810 to busyout if both Ethernet port 0 and serial port 0 go out of service:
router(config)# voice-port 0:6 router(config-voiceport)# busyout monitor ethernet 0 router(config-voiceport)# busyout monitor serial 0 router(config-voiceport)#
Related Commands Related Commands
| Command | Description |
busyout forced | Forces a voice port into the busyout state. |
Configures a voice port to monitor a local Ethernet interface for events that would trigger a voice-port busyout. | |
Configures a voice port to enter the busyout state if an RTR probe signal returned from a remote, IP-addressable interface crosses a specified delay or loss threshold. | |
busyout seize | Changes the busyout seize procedure for a voice port. |
show voice busyout | Displays information about the voice busyout state. |
To create a voice class for local voice busyout functions, use the voice class busyout global configuration command. Enter the no form of this command to delete the voice class.
voice class busyout tagSyntax Description
tag | A unique identification number assigned to one voice class. The range is 1 to 10000. |
Defaults
No voice class is configured for busyout functions.
Command Modes
Global configuration.
Command History
| Release | Modification |
|---|---|
12.1(3)T | This command was introduced. |
Usage Guidelines
You can apply a busyout voice class to multiple voice ports.
You can assign only one busyout voice class to a voice port. If a second busyout voice class is assigned to a voice port, the second voice class replaces the one previously assigned
If you assign a busyout voice class to a voice port, you may not assign separate busyout commands directly to the voice port, such as busyout monitor serial, busyout monitor ethernet, or busyout monitor probe.
Examples
The following example configures busyout voice class 20, in which the connections to two remote interfaces are monitored by an RTR probe with a G.711ulaw profile, and voice ports are busied out whenever both links have a packet loss exceeding 10 percent and packet delay time exceeding 2 seconds:
router(config)# voice class busyout 20 router(config-voice-class)# busyout monitor probe 209.165.202.128 g711u loss 10 delay 2000 router(config-voice-class)# busyout monitor probe 209.165.202.129 g711u loss 10 delay 2000 router(config-voice-class)#
The following example configures busyout voice class 30, in which voice ports are busied out when serial ports 0/0, 1/0, 2/0, and 3/0 go out of service.
router(config)# voice class busyout 30 router(config-voice-class)# busyout monitor serial 0/0 router(config-voice-class)# busyout monitor serial 1/0 router(config-voice-class)# busyout monitor serial 2/0 router(config-voice-class)# busyout monitor serial 3/0 router(config-voice-class)#
Related Commands Related Commands
| Command | Description |
Configures a voice port to monitor a local Ethernet interface for events that would trigger a voice-port busyout. | |
Configures a voice port to monitor a serial interface for events that would trigger a voice-port busyout. | |
Configures a voice port to enter the busyout state if an RTR probe signal returned from a remote, IP-addressable interface crosses a specified delay or loss threshold. | |
show voice busyout | Displays information about the voice busyout state. |
ABCD signaling—Four-bit telephony line signaling coding in which each letter of "ABCD" represents one of the four bits. This is often associated with CAS or Robbed-Bit signaling on a T1 or E1 telephony trunk.
AVBO—Advanced Voice Busy Out.
CLI—Command line interface.
CODEC—Coder-Decoder. An integrated circuit device that typically uses pulse code modulation to transform analog signals into a digital bit stream and digital signals back into analog signals. In Voice over IP, Voice over Frame Relay, and Voice over ATM, a DSP software algorithm used to compress/decompress speech or audio signals.
DLCI—Data-link connection identifier.
Dial peer—An addressable call endpoint that contains configuration information including voice protocol, a CODEC type, and a telephone number associated with the call endpoint. There are four kinds of dial peers: POTS, VoIP, VoFR, and VoATM.
E&M—Stands for 2-wire or 4-wire interfaces with separate signaling paths (from "Ear and Mouth", also "recEive and transMit"). E&M is a trunking arrangement generally used for two-way switch-to-switch or switch-to-network connections. Cisco's analog E&M interface is an RJ-48 connector that allows connections to PBX trunk lines (tie lines). E&M connections are also available on E1 and T1 digital interfaces.
E1—European equivalent of T1. 32-64kbps channels include 1-channel for framing and 1-channel for signaling information. The clock rate is 2.048 Mhz.
ICPIF—Calculated Planning Impairment Factor.
LVBO—Local Voice Busy Out.
PBX—Private Branch Exchange. A privately owned central switching office.
POTS—Plain old telephone service. Basic telephone service supplying standard single line telephones, telephone lines, and access to the PSTN.
PSTN—Public Switched Telephone Network.
RTR—Response Time Reporter.
Switched calls—Switched calls are normal telephone calls when a user picks up a phone, hears a dial tone, and enters the destination phone number to reach the other phone.
T1—Digital carrier facility. T1 transmits DS-1-formatted data at 1.544 Mbps through the telephone-switching network by using AMI or B8ZS coding.
Trunk—Service that allows quasi-transparent connections between two PBXs, a PBX and a local extension, or some other combination of telephony interfaces with signaling passed transparently through the packet data network.
Posted: Wed Sep 27 12:46:41 PDT 2000
Copyright 1989-2000©Cisco Systems Inc.