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Table Of Contents
Configuring T1 CAS for Voice over IP on the Cisco AS5800 and Cisco AS5850
Channelized T1 Robbed Bit Features
Related Features and Technologies
Supported Standards, MIBs, and RFCs
Verifying Service Provider T1 CAS
Configuring T1 CAS for Voice over IP on the Cisco AS5800 and Cisco AS5850
Feature History
This feature module describes the Configuring T1 CAS for Voice over IP on the Cisco AS5800 and Cisco AS5850 feature and includes the following sections:
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Supported Standards, MIBs, and RFCs
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Feature Overview
This feature adds support for T1 Channel Associated Signaling (CAS) and support for E1 R2 signaling to the Cisco AS5800 and Cisco AS5850 with the Voice Feature Card (VFC).
CAS is the transmission of signaling information within the voice channel. Various types of CAS signaling are available in the T1 world. The most common forms of CAS signaling are loop-start, ground-start EANA, and E&M. The biggest disadvantage of CAS signaling is its use of user bandwidth to perform signaling functions. CAS signaling is often referred to as robbed-bit-signaling because user bandwidth is being "robbed" by the network for other purposes. In addition to receiving and placing calls, CAS signaling also processes the receipt of DNIS and ANI information, which is used to support authentication and other functions.
The service provider application for T1 CAS includes connectivity to the public network using T1 CAS from the Cisco AS5800 to the end office switch. In this configuration, the Cisco AS5800 captures the dialed-number or called-party number information and passes it along to the upper level applications for IVR script selection, modem pooling, and other applications. Service providers also require access to calling party number, ANI, for user identification, for billing account number, and in the future, more complicated call routing.
Service providers who implement VoIP include traditional voice carriers, new voice and data carriers, and existing Internet service providers. Some of these service providers might use subscriber side lines for their VoIP connectivity to the PSTN; others will use tandem-type service provider connections.
The new functionality of CAS for VoIP includes all the CAS and E1/R2 signaling already supported for the Cisco AS5800 in data applications, with the addition of dialed-number and calling-party number capture whenever available.
The implementation of this feature supports the following T1 CAS signaling systems for VoIP applications:
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In the original Wink Start Protocol, the terminating side responds to an off-hook from the originating side with a short wink (transition from on-hook to off-hook and back again). This wink tells the originating side that the terminating side is ready to receive addressing digits. After receiving addressing digits, the terminating side then goes off-hook for the duration of the call. The originating endpoint maintains off-hook for the duration of the call.
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In Feature Group D Wink Start with Wink Acknowledge Protocol, the terminating side responds to an off-hook from the originating side with a short wink (transition from on-hook to off-hook and back again) just as in the original Wink Start. This wink tells the originating side that the terminating side is ready to receive addressing digits. After receiving addressing digits, the terminating side then provides another wink (called an Acknowledgment Wink) that tells the originating side that the terminating side has received the dialed digits. The terminating side then goes off-hook to indicate connection when the ultimate called endpoint has answered. The originating endpoint maintains off-hook for the duration of the call.
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In the Immediate Start Protocol, the originating side does not wait for a wink before sending addressing information. After receiving addressing digits, the terminating side then goes off-hook for the duration of the call. The originating endpoint maintains off-hook for the duration of the call.
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Channelized T1 Robbed Bit Features
Internet service providers can provide switched 56-kbps access to their customers using the Cisco AS5800. The subset of T1 CAS (robbed bit) supported features are as follows:
Supervisory: Line Side
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Supervisory: Trunk Side
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Informational: Line Side
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Informational: Trunk Side
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Benefits
The T1 CAS interface is used for both connection to a private PBX, and to the PSTN. This feature is required by both Enterprise customers and Service Providers in North America. For most enterprise customers, T1 CAS is the only type of line they use from the PSTN, and for connecting to their PBX, E&M may be the only option.
Related Features and Technologies
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Supported Platforms
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Table 1 Cisco IOS Release and Platform Support for this Feature
Cisco AS5800
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Not supported
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Cisco AS5850
Not supported
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X
Determining Platform Support Through Cisco Feature Navigator
Cisco IOS software is packaged in feature sets that support specific platforms. To get updated information regarding platform support for this feature, access Cisco Feature Navigator. Cisco Feature Navigator dynamically updates the list of supported platforms as new platform support is added for the feature.
Cisco Feature Navigator is a web-based tool that enables you to determine which Cisco IOS software images support a specific set of features and which features are supported in a specific Cisco IOS image. You can search by feature or release. Under the release section, you can compare releases side by side to display both the features unique to each software release and the features in common.
To access Cisco Feature Navigator, you must have an account on Cisco.com. If you have forgotten or lost your account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check will verify that your e-mail address is registered with Cisco.com. If the check is successful, account details with a new random password will be e-mailed to you. Qualified users can establish an account on Cisco.com by following the directions at http://www.cisco.com/register.
Cisco Feature Navigator is updated regularly when major Cisco IOS software releases and technology releases occur. For the most current information, go to the Cisco Feature Navigator home page at the following URL:
Availability of Cisco IOS Software Images
Platform support for particular Cisco IOS software releases is dependent on the availability of the software images for those platforms. Software images for some platforms may be deferred, delayed, or changed without prior notice. For updated information about platform support and availability of software images for each Cisco IOS software release, refer to the online release notes or, if supported, Cisco Feature Navigator.
Supported Standards, MIBs, and RFCs
Standards
None.
MIBs
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To obtain lists of MIBs supported by platform and Cisco IOS release and to download MIB modules, go to the Cisco MIB web site on Cisco Connection Online (CCO) at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.
RFCs
None.
Prerequisites
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Configuration Tasks
The sample configuration is only intended as an example of how to use the commands to configure T1 CAS. It is not an example of a complete configuration for setting up the entire signaling for a telco network.
To configure T1 CAS for use with VoIP, perform the following tasks:
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The following sample configuration is an example of how to configure the voice ports as ds0-group for the channelized T1 lines.
Verifying Service Provider T1 CAS
To verify your controller is up and running and no alarms have been reported:
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5800# sh cont t1 1/0/0T1 1/0/0 is up.Applique type is Channelized T1Cablelength is long gain36 0dbNo alarms detected.alarm-trigger is not setFraming is ESF, Line Code is B8ZS, Clock Source is Line.Data in current interval (180 seconds elapsed):0 Line Code Violations, 0 Path Code Violations0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail SecsNote the following:
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Tip
Configuration Examples
Service Provider T1 CAS Example
The output shown below is the result of using the show running-config command.
version 12.1service timestamps debug datetime msec localtime show-timezoneservice timestamps log datetime msec localtime show-timezoneservice password-encryption!hostname travis-nas-01!aaa new-modelaaa authentication login default localaaa authentication login NO_AUTHENT noneaaa authorization exec default local if-authenticatedaaa authorization exec NO_AUTHOR noneaaa authorization commands 15 default local if-authenticatedaaa authorization commands 15 NO_AUTHOR noneaaa accounting exec default start-stop group tacacs+aaa accounting exec NO_ACCOUNT noneaaa accounting commands 15 default stop-only group tacacs+aaa accounting commands 15 NO_ACCOUNT noneenable secret 5 $1$LsoW$K/qBH9Ih2WstUxvazDgmY/!username admin privilege 15 password 7 06455E365E471D1C17username gmcmilla password 7 071824404D06140044username krist privilege 15 password 7 0832454D01181118!!!!call rsvp-syncshelf-id 0 router-shelfshelf-id 1 dial-shelf!!!resource-pool disable!modem-pool Defaultpool-range 1/2/0-1/2/143,1/3/0-1/3/143!modem-pool accounts!modem-pool accounts1!modem-pool accounts2!clock timezone CST -6clock summer-time CST recurring!!!!ip subnet-zeroip domain-name cisco.comip name-server 172.22.53.210ip name-server 171.69.2.133ip name-server 171.69.2.132ip name-server 171.69.11.48!isdn switch-type primary-5ess!!!!!!!controller T1 1/0/0framing esflinecode b8zsds0-group 1 timeslots 1-24 type e&m-fgb!controller T1 1/0/1framing esflinecode b8zsds0-group 1 timeslots 1-24 type e&m-fgb!controller T1 1/0/2framing esflinecode b8zsds0-group 1 timeslots 1-24 type e&m-fgb!controller T1 1/0/3framing esflinecode b8zsds0-group 0 timeslots 1-24 type e&m-fgb dtmf dnis!controller T1 1/0/4Command 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 references.
ds0-group
To configure a channel group using CAS signaling, the ds0-group command is used to specify the channels/timeslots to be allocated for the CAS group and the CAS signaling type. Use the no form of this command to disable channel associated signaling for one or more timeslots.
ds0-group channel timeslots range type signal [[tone] [service]]
no ds0-group channel timeslots range type signal [[tone] [service]]
New service type attributes have been added to the ds0 group command.
The service types are:
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For e&m-fgb and e&m fgd, there are also tone type:
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Syntax Description
Defaults
ds0-group 0 timeslots 1-24 type e&m-fgb dtmf
Command History
Related Commands
Controller configuration.
Usage Guidelines
Use this command to enable an integrated modem to receive and transmit incoming and outgoing call signaling (such as on-hook and off-hook) through each T1 controller.
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By configuring DNIS as part of the ds0-group command, the system can collect DNIS digits for incoming calls which can be directed as VoIP calls, or alternately can be redirected to specific modem pools setup for different customers or uses. To support modems you must be running MICA modems in the system and have at least 10% of your total modems in the default modem pool.
The following example configures the required signaling to support modem pooling and the digital number identification service (DNIS) over channelized T1 lines on a Cisco AS5800.
Examples
Router# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# controller t1 1/0/0Router(config-controller)# ds0-group 0 timeslots 1-24 type e&m-fgb dtmf dnisRouter(config-controller)# exitRouter(config)#Router(config)# modem-pool accounts1Router(config-modem-p)# pool-range 30Router(config-modem-p)# called-number 2000 max-conn 1Router(config-modem-p)# exitRouter(config)#
Note
Glossary
ANI—Automatic number identification (calling party number).
CAS—Channel associated signaling.
CO—Central office.
DNIS—Dialed number identification service. Same as called party number.
DSP—Digital signal processor.
DTMF—Dual tone multi-frequency.
E&M—Ear and mouth. A signaling technique for two and four wire telephone and trunk interfaces.
FXS—Foreign Exchange Subscriber (as in FXS-loop-start and FXS-ground-start). FXS loop and ground start protocols are a type of signaling used to indicate the beginning of a call. The FXS interface is used on the line-side access to CO (for example, communication between CO and key system).
ITU—International Telecommunication Union.
MF—Multiple Frequency, an interoffice address signaling method in which 10 decimal digits and five auxiliary signals are each represented by a pair of the following frequencies: 700, 900, 1100, 1300, 1500 and 1700 Hz.
PSTN—Public Switched Telephone Network.
SAS—Special Exchange Subscriber (as in SAS loop-start and ground-start). Identical to FXS loop and ground start in functionality, but use of the A and B bits are different. (SAS transmitted B Bits are complementary to FXS transmitted B bits. SAS received A bits are complementary to FXS received A bits).
VFC—Voice feature card. The voice processing card which resides in one of the slots in the Cisco AS5800 platform. Up to five DSP modules (DSPM) can be installed onto the VFC to perform voice processing for up to 30 B channels and potentially 60 B channels. The VFC is a multi-DSP coprocessing card and software package that adds VoIP capabilities to the Cisco AS5800.
VoIP—Voice over IP. The ability to carry normal telephony-style voice over an IP-based internet with POTS-like functionality, reliability, and voice quality. VoIP is a blanket term which generally refers to Cisco's standards-based (for example, H.323) approach to IP voice traffic.
Posted: Wed Sep 26 05:13:13 PDT 2007
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