Configuring Cisco 1003, 1600, 1700, 2500, 2600 and 3600 Routers for Data-over-Voice with Telstra 'ISDN Home'
Compiled by Craig Dewick (note the 'poisoned' email address!)


Background and Introduction

WARNING: Tel$tra has announced that from the end of 2008, the company will be cancelling the availability of ISDN Home, which effectively means the use of the special bearer cap value which sets up date-over-voice in the exchange equipment is either going to be blocked, or completely disabled. Please make sure you set up alternative arrangements (ie. DSL, etc. if you can actually get it) before Tel$tra stops offering 'residential-grade' ISDN services!

If you happen to be in one of the many areas in Australia where it's impossible to get any form of DSL, or can't get reliable wireless network service from any of the key providers, your only option will be to resort to dial-up Internet services or go with very expensive satellite services. Not really a whole lot of choice for the 15 or so percent of Australia that cannot get DSL! Tel$tra acts like a bank - not giving a shit about customers in preference to sucking up to shareholders.

This page is home to my expanding archive of data and information about using model 1003, 1603, 1720/21, etc. ISDN routers from Cisco to support Data-over-Voice (DoV) with Telstra's ISDN Home residential-tariff ISDN service.

Cisco 1003's (and 1004's), along with some of the 1600-series routers, have a single on-board BRI (Basic-Rate ISDN) port as the primary 'external' network interface. The Cisco 1004 (and 1601) cannot be used in Australia because it has an integrated network terminator and is not Austel-certified. Likewise the WIC-1BU along with the NM-4BU and NM-8BU network module cards cannot be used in Australia - only the WIC-1BS/T, NM-4BS/T and NM-8BS/T (and a few others which provide PRI - Primary Rate ISDN [not the subject of this web page] - interfaces compatible with Australian ETSI-style ISDN exchange equipment) can be used.

Other Cisco routers (such as the 16xx, 17xx, 26xx and 36xx series) can have varying combinations of single-port and/or multiple-port BRI cards fitted (see the picture section below) and they are configured to support DoV-based in-dialling or out-dialling in a similar way to the native BRI interface in a 1003, 1603, etc..

Most Cisco routers (along with almost all of Cisco's other products) run a version of Cisco's special operating system called IOS. Cisco supplies (to contract customers) access to an FTP site where precompiled binary images of IOS for every supported model of router, switch, etc. are available. These images are available in different configurations depending on the specific 'feature sets' required by the customer. In the case of 1003's, and some other models such as 16xx's and 17xx's, since Cisco don't sell them new anymore, the range of feature sets is limited because of the maximum RAM capacity and speed of the core processor.

I have some Cisco IOS images available which I have obtained for/from routers I have used and collected from other sources. More about this later... 8-)

Technical Aspects of Data-over-Voice

Data-over-Voice (DoV) is a way for the equipment in the telco exchange to transmit information for the call made on a particular ISDN 'B' channel using voice-grade transmission paths if there are no data-grade transmission paths available at any one point between the ISDN line at the originating location and the ISDN line at the destination.

During the setup of an ISDN call, a number called the bearer cap (meaning literally 'bearer capability') is transmitted as part of the ISDN q.931 setup messages, and this number is basically a request to the network exchange equipment to ask if a particular type of encoding is allowed. If the telco exchange equipment allows it, this is indicated back to the originating equipment and the call is attempted to the destination.

For DoV calls made by any ISDN equipment in Australia, the bearer cap setting must be 0x8090A3 (which indicates the originating equipment wants to make a voice/speech call using a-law encoding). A common problem is that equipment with incorrect or older software will try to request a bearer-cap setting of 0x8090A2 which is for a voice/speech call using u-law encoding, and that's not supported in the Australian ISDN standards.

To gain the benefit of Telstra's untimed local voice calls with their ISDN Home service, you must ensure that the bearer cap is set properly or you will be charged full data-call rates of $1.10 per hour! 8-)

With Cisco routers you can confirm that the correct bearer cap value is presented by enable ISDN q931 debugging and triggering the router into making a call on the relevant ISDN interface. This will produce a display of the ISDN q.931 messages transmitted during call setup and show what bearer cap value is being used.

Hardware Requirements for Cisco 1003's

Cisco 1003's have very limited memory expandability. To run a DoV-capable version of IOS, they must have a minimum of 8 MB of RAM installed. RAM modules for the 1000-series routers are available in 4, 8 or 16 MB sizes, but since they only take one module per router, you should go for a 16 MB module if you have a 1003 allow the router to have plenty of RAM spare for handling any unusual config requirements you might have.

NOTE: Some 16 MB RAM modules will not work in 1003's even though they're sold as suitable for them. I have had some bad experiences with a lot of 16 MB modules giving parity errors which make IOS abort with a bus error, so be careful.

The 1003's also have a PCMCIA slot for a flash memory card which opens out to the rear. A flash card can be used to store the compressed IOS image which is loaded directly into RAM, uncompressed, and executed after the hardware self-tests are completed. The 1003's, like nearly all other Cisco routers, can alternatively download the compressed IOS image via tftp from another host, but storing it locally on a flash card is much better for recovery from power failures, etc.

Both 2 or 4 MB flash cards are supported, but because the compressed 12.x IOS image which includes DoV support is larger than 2 MB, you will need to replace the flash card with a 4 MB one if your router doesn't have that size already.

Terms: I can source memory components for any Cisco (or Sun) product directly from suppliers in the US. If you would like me to source something for you, please email me at SRK (remove 'poison. to make the email address valid) with your requirements. I can accept credit card payments through PayPal or PayMate, and from Australian buyers I also accept EFT (ie. direct-deposit), etc. Pre-payment of all orders is encouraged so I can secure the fastest possible turnaround on getting your items from my supplier in the US. If you'd like to read the full terms and conditions, go over to my SRK website.

Downloads

Cisco IOS Images

Cisco IOS images are pre-compressed binary files (indicated by the .bin filename extension) and when loaded by the appropriate model of router the image that's been loaded is uncompressed internally before execution is passed to it.

Cisco IOS Images for Data-over-Voice Support
These are IOS images I have used on routers and know that they support DOV properly
Router Family IOS Filename Fetch Image Size RAM Requirements Notes
1000 series (1003, 1004)
c1000-y-mz.121-8.bin
2.49 MB
8 MB minimum
on-board BRI
1000 series (1003, 1004)
c1000-y-mz.121-16.bin
2.53 MB
8 MB minimum
on-board BRI
2600 series (2610, 2611, 2620, 2621)
c2600-io3-mz.122-10.bin
5.46 MB
16 MB minimum
ISDN WIC or NM required
3620
c3620-io3-mz.122-3.bin
6.01 MB
16 MB minimum
ISDN WIC or NM required
I've got plenty more IOS images available that I've collected from various 'interesting' sources researched mostly via Google! Check the full collection to see if one of the images is right for your application. If you have some IOS images you'd like to contribute to the collection, please get in touch (remember to 'unpoison' the email address to remove the anti-spam feature!)

Cisco 1003 and 1603 routers have an on-board BRI port but do not have an integrated NT1. They can be used with any basic-rate ISDN service in Australia. Cisco 1004 and some other routers in the Cisco range also have an on-board BRI port but they do have an integrated NT1 and are not certified for use in Australia. Using a 1004 or other non-compliant ISDN device with any Telstra ISDN service is a breach of Austel regulations.

Some of the Cisco 2500 routers also have one or two on-board BRI ports in addition to other types of interfaces.

Cisco 1700, 2600 and 3600 routers are fully-modular designs and have no on-board ISDN hardware in their raw configurations. They require ISDN WIC's (WAN Interface Cards) and/or NM's (Network Modules) to gain ISDN support.

Cisco Technical Documentation

The following Cisco documents contain more useful information about the routers mentioned on this page, and configuring Cisco routers in general for supporting DoV, plus other useful reference documents:

Picture Gallery

I've been collecting some pictures of Cisco ISDN hardware (routers, cards, etc.) which you might find useful for reference purposes, etc.:

This page has been accessed times.


If there is anything you'd like to ask me, send me some email. Remember to 'un-poison' the email address to remove the anti-spam feature.


Back to my electrotechnology home page