Table Of Contents
Analog DID for Cisco 2600 and Cisco 3600 Series Routers
Supported Standards, MIBs, and RFCs
Configuring Voice Ports to Support Direct Inward Dialing
Direct Inward Dialing Configuration Steps
Verifying Direct Inward Dialing Voice-Port Configuration
Analog DID for Cisco 2600 and Cisco 3600 Series Routers
Feature History
12.1(5)XM
This feature was introduced on Cisco 2600 and Cisco 3600 series routers
12.2(2)T
This command was integrated into Cisco IOS Release 12.2(2)T
This document describes Cisco IOS configuration for Direct Inward Dialing (DID) as supported on Cisco 2600 and Cisco 3600 series modular access routers. This document includes the following sections:
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Supported Standards, MIBs, and RFCs
Feature Overview
Direct Inward Dialing (DID) is a service offered by telephone companies that enables callers to dial directly to an extension on a Private Branch Exchange (PBX) without the assistance of an operator or automated call attendant. This service makes use of DID trunks, which forward only the last three to five digits of a phone number to the PBX. If, for example, a company has a PBX with extensions 555-1000 to 555-1999, and a caller dials 555-1234, the local CO would forward 234 to the PBX. The PBX would then ring extension 234. This entire process is transparent to the caller.
When this feature is configured, a voice-enabled Cisco 2600 and Cisco 3600 series router can receive calls from a DID trunk and connect them to the appropriate extensions. The DID state machine is identical to the E&M state machine and uses one of the following signaling types:
Immediate Start
The originating end seizes the line by going off hook and, without waiting for a response, it begins to outpulse digits. The address signaling used with immediate-start signaling consists only of dial-pulsing.
Wink-Start
The originating end seizes the line by going off-hook. It waits for acknowledgement from the other end before outpulsing digits. This serves as an integrity check that will identify a malfunctioning trunk and allow the network to send a re-order tone to the calling party.
Delay Dial
The originating end seizes the line and waits 200 ms to see if the far end is on-hook. If so, the originating end then outpulses digits. If the far end is off-hook, the originating end waits until the far end is on-hook before outpulsing digits.
Figure 1 shows a hypothetical topology where a user connected to the PSTN (Caller A) dials various numbers and is connected to the appropriate extensions on a PBX.
Figure 1 DID Support for Cisco 2600 and Cisco 3600 Series Routers
555-1234
234
User C
555-1345
345
User D
555-1456
456
User B
555-1678
678
No dial-peer match found; fast busy tone is played
Benefits
The DID feature makes it seem that all extensions on a PBX have direct lines to the PSTN. This is accomplished without the expense associated with connecting each extension to the PSTN. In addition to saving the cost of an operator, DID gives callers the feeling that they are calling an individual, rather than a large company.
Restrictions
Direct Inward Dialing can be configured with the following restrictions:
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Related Documents
For information on installing and configuring Cisco 2600 and Cisco 3600 routers, refer to the following online documents:
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For more information about voice configuration, see the following Cisco IOS Release 12.1 guides:
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The following configuration guides describe the configuration of IP, Frame Relay, and ATM:
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The following online feature documentation describes new voice-port features that are available in Cisco IOS Release 12.1(2)T and available with Direct Inward Dialing:
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Supported Platforms
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Supported Standards, MIBs, and RFCs
Standards
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MIBs
None.
RFCs
None.
Prerequisites
The following hardware, software, and basic configurations are required to support Direct Inward Dialing:
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Configuration Tasks
After verifying that your router meets the requirements listed in the "Prerequisites" section, see the following sections for configuration tasks for DID. Each task in the list is identified as either optional or required:
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Configuring Voice Ports to Support Direct Inward Dialing
Follow these steps in order to configure voice ports for Direct Inward Dialing. Not all commands required to configure voice ports appear here. Use the reference information in the "Related Documents" section to find out more about voice-port configuration.
Direct Inward Dialing Configuration Steps
Verifying Direct Inward Dialing Voice-Port Configuration
To verify voice-port configuration, enter the show voice port command. You can specify a voice port or view the status of all configured voice ports. In the following example, the specified port is configured for DID.
Router# show voice port 1/1/0Foreign Exchange Station with Direct Inward Dialing (FXS-DID) 1/1/0 Slot is1, Sub-unit is 1, Port is 0Type of VoicePort is DID-INOperation State is DORMANTAdministrative State is UPNo Interface Down FailureDescription is not setNoise Regeneration is enabledNon Linear Processing is enabledMusic On Hold Threshold is Set to -38 dBmIn Gain is Set to 0 dBOut Attenuation is Set to 0 dBEcho Cancellation is enabledEcho Cancel Coverage is set to 8 msPlayout-delay Mode is set to defaultPlayout-delay Nominal is set to 60 msPlayout-delay Maximum is set to 200 msPlayout-delay Minimum mode is set to default, value 4 msPlayout-delay Fax is set to 300 msConnection Mode is normalConnection Number is not setInitial Time Out is set to 10 sInterdigit Time Out is set to 10 sCall Disconnect Time Out is set to 3 sRinging Time Out is set to 180 sWait Release Time Out is set to 3 sCompanding Type is u-lawRegion Tone is set for USAnalog Info Follows:Currently processing noneMaintenance Mode Set to None (not in mtc mode)Number of signaling protocol errors are 0Impedance is set to 600r OhmStation name Chalil Mohanan, Station number 1234567Voice card specific Info Follows:Signal Type is wink-startDial Type is dtmfIn Seizure is inactiveOut Seizure is inactiveDigit Duration Timing is set to 100 msInterDigit Duration Timing is set to 100 msPulse Rate Timing is set to 10 pulses/secondInterDigit Pulse Duration Timing is set to 750 msClear Wait Duration Timing is set to 400 msWink Wait Duration Timing is set to 200 msWait Wink Duration Timing is set to 550 msWink Duration Timing is set to 200 msDelay Start Timing is set to 300 msDelay Duration Timing is set to 2000 msDial Pulse Min. Delay is set to 140 msPercent Break of Pulse is 60 percentAuto Cut-through is disabledDialout Delay for immediate start is 300 msCommand Reference
This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.1 command reference publications and in Cisco IOS Release 12.1 feature modules.
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signal did
To enable Direct Inward Dialing on a voice port, use the signal did voice-port configuration command. To disable the command's effect, use the no form of this command.
signal did {immediate-start | wink-start | delay-start}
no signal did
Syntax Description
Defaults
The default value is immediate-start
Command Modes
Voice-port configuration
Command History
12.1(5)XM
This feature was introduced on Cisco 2600 and Cisco 3600 series routers
12.2(2)T
This command was integrated into Cisco IOS Release 12.2(2)T
Usage Guidelines
The signal did command enables a voice port to receive calls from a DID trunk.
This command applies to Cisco 2600 and Cisco 3600 series routers.
Examples
The following example configures a voice port on a Cisco 2600 or 3600 router where DID information is received:
voice-port 1/0/1signal did immediate-startGlossary
ATM—Asynchronous Transfer Mode. International standard for cell relay in which multiple service types (such as voice, video, or data) are conveyed in fixed-length (53-byte) cells. Fixed-length cells allow cell processing to occur in hardware, thereby reducing transit delays. ATM is designed to take advantage of high-speed transmission media such as E3, SONET, and T3.
CAS—channel-associated signaling. Trunk signaling (for example, in a T1 line) in which control signals, such as those for synchronizing and bounding frames, are carried in the same channel along with voice and data signals.
CCS—common channel signaling. Trunk signaling (for example, using Primary Rate Interface) in which a control channel carries signaling for separate voice and data channels.
CO—central office. Local telephone company office to which all local loops in a given area connect and in which circuit switching of subscriber lines occurs.
codec—Coder-decoder. Device that typically uses pulse code modulation to transform analog signals into a digital bit stream and digital signals back into analog.
CTI—Computer telephony integration.
DTMF—Dual-tone multifrequency. Use of two simultaneous voice-band tones for dialing (such as touch tone).
DSP—digital signal processor.
DID—Direct Inward Dialing.
E&M—rEceive and transMit, or Ear and Mouth. Type of signaling originally developed for analog two-state voltage telephony using the ear and mouth leads; in digital telephony, uses two bits.
ETSI—European Telecommunication Standards Institute.
FXO—Foreign Exchange Office. A voice interface emulating a PBX trunk line to a switch or telephone equipment to a PBX extension interface.
FXS—Foreign Exchange Station. A voice interface for connecting telephone equipment, emulates the extension interface of a PBX or the subscriber interface for a switch.
IETF—Internet Engineering Task Force
ISDN—Integrated Services Digital Network. Communication protocol, offered by telephone companies, that permits telephone networks to carry data, voice, and other source traffic.
POTS—plain old telephone service
PSTN—Public Switched Telephone Network. General term referring to the variety of telephone networks and services in place worldwide.
SNMP—Simple Network Management Protocol. Network management protocol used almost exclusively in TCP/IP networks. SNMP provides a means to monitor and control network devices, and to manage configurations, statistics collection, performance, and security.
T1—Digital WAN carrier facility. T1 transmits DS 1-formatted data at 1.544 Mbps through the telephone switching network, using alternate mark inversion or B8ZS coding.
T1 trunk—Digital WAN carrier facility. See T1.
TDM—time-division multiplexing
Trunk—Physical and logical connection between two switches across which network traffic travels. A backbone is composed of a number of trunks.
