Telecom Informer

    

by The Prophet

Hello, and greetings from the Central Office!

And welcome to The Telecom Informer!  In this new column I'll be your guide through the exciting, dynamic, and rapidly evolving world of telecommunications.

Wait a minute!  Exciting?  Dynamic?  Rapidly evolving?  These are, you might think, descriptions that are much more applicable to the Internet, world trade, or the Bush administration's latest excuse for invading Iraq.  While other areas of technology are definitely interesting, and wireline telephony hasn't changed much in the last 15 years, telecommunications is a fast-changing, growing, and evolving industry.

Of course, it can be a challenge these days to define just what "telecommunications" is.

Things were so much simpler in the days of the Bell System!  Certainly, you can still make a call using a traditional landline telephone.  However, you could also make the same call using any of five different cellular technologies (and that's just in North America), dozens of IP-based telecommunications services, nearly a half-dozen satellite phone services, or any combination of the above.

In this issue, I'll show you how to add a second phone line to your house for less than $20 - with no monthly fee!

What happens when you give a Swedish massage to an AT&T CallVantage adapter?  Free World Dialup ecstasy!  Confused?  Read on, and I'll explain.

Voice over IP (VoIP) landline replacement services such as Vonage, Packet8, and AT&T CallVantage have skyrocketed in popularity over the past year.  Taking a cue from the wireless phone industry, providers of these services offer gateway adapters at very low prices - even free (after rebate, of course)!

The catch, as you might expect, is that the hardware you buy is "locked."

You can only use it with services provided by the company that sold it to you, even if it is technologically compatible with other services.  If you want to change VoIP service providers or even try a free one (such as Free World Dialup), you have to change your hardware.

This big hassle is made even bigger by the fact that VoIP adapters are designed to sit at the front of your network, controlling all traffic behind it.  This approach is taken to improve Quality of Service (QoS) on voice calls by limiting the bandwidth used by other simultaneous Internet traffic.  It's undoubtedly also taken to ensure that switching providers is a major ordeal.

VoIP Hardware

I got interested in the D-Link DVG-1120M adapter, which is designed for the AT&T CallVantage service, because I'm thrifty.

Well, that's how I describe myself anyway; most of my friends describe me using less flattering terms like "cheap bastard."

In any event, the AT&T CallVantage adapter is much less expensive than most other VoIP gateways.  As of this writing, you can buy a D-Link DVG-1120M for less than $20 at Fry's Electronics.

But, following the tried-and-true Gillette "give away the razor and make money on the blades" business model, the AT&T CallVantage service sells for about $30 per month for unlimited usage.

Of course, this is more expensive than competitive services such as Vonage or Packet8, and it's a heck of a lot more than free (my preferred cost).

My goal, which I successfully accomplished, was to unlock and use the adapter with the Free World Dialup service.  This is a free SIP-based VoIP service that allows not only free calling to any other Free World Dialup user, but free outgoing calls to any landline toll-free (freephone) number in the U.S. and numerous other countries (including Germany, the U.K., and the Netherlands to name a few).

Even better, there are numerous landline gateway services that provide free, anonymous landline phone numbers for incoming calls to your Free World Dialup line.

Hacking the D-Link DVG-1120M

I quickly encountered a seemingly insurmountable challenge.

Although the de-facto standard protocol for most VoIP communications is SIP, AT&T CallVantage uses the less popular Media Gateway Control Protocol (MGCP).

Fortunately, after doing some further research, I learned that the DVG-1120M has a twin called the DVG-1120S.

The hardware on both units is identical, but the firmware on the DVG-1120S supports SIP instead of MGCP.  Better yet, I learned that it is possible to flash the DVG-1120M with the Swedish firmware for the DVG-1120S (don't worry, the menus are in English), which allows the use of Free World Dialup and other SIP-based services.

While the hack isn't complicated, it's pretty long and involved so I've broken it out into detailed steps.  To convert the DVG-1120M to a DVG-1120S and use it with Free World Dialup, follow the procedures below.

Getting Started

1.)  Obtain the following prerequisites:

2.)  Power on the DVG-1120M.

3.)  Using the Ethernet cable that came with the DVG-1120M, plug it directly into the Ethernet port on your computer.

Apply the Runtime Update

1.)  Go to a command prompt and type the following command: ipconfig /all

  • If the IP address of your computer is in the 192.168.15.x subnet, your DVG-1120M is properly connected.  Proceed to the next step.

  • If the IP address of your computer is not in the 192.168.15.x subnet, your DVG-1120M is not properly connected.  Verify all connections.  This should fix the problem.  If the issue is still not resolved, perform a manual factory reset on the DVG-1120M unit following the instructions in the D-Link documentation.

2.)  Start Internet Explorer and go to the following URL: http://192.168.15.1

3.)  Click "Login to the Web-Based Management Module".

4.)  Click "Advanced".  This will prompt you for a user name and password.

5.)  Type admin in the "Username" and "Password" text boxes and then click O.K.

6.)  Using Windows Explorer, go to the folder where the DlinkTftpServer.exe, 1120S_promcode_b09.bin, and 1120S_runtime_s08.tfp files are located, and then start the DlinkTftpServer.exe program.

7.)  Note:  If you are running a firewall, you may need to either disable it or add the DlinkTftpServer.exe program to the Exceptions list.

8.)  Switch back to the Administration web page.  In the left-hand navigation pane, click "Firmware Update".

9.)  In the "TFTP Server Address" text boxes, type the IP address of your computer (as shown in Step 1).

10.)  In the "Firmware Update" drop-down list, select "Enabled".

11.)  In the "File Name" text box, type 1120S_runtime_s08.tfp and then click "Save".  This will apply the runtime update.  If you are impatient, you can view the Status display in the DlinkTftpServer.exe program to confirm that the upgrade is in progress.

12.)  After the runtime update is applied, click "Save Changes and Reboot System Now" and then click "Save".  The DVG-1120M will make an audible clicking sound and it will then reboot.

13.)  Close Internet Explorer and the DlinkTftpServer.exe program.

Apply the Firmware Update

1.)  Go to a command prompt and type the following command: ipconfig /all

  • If the IP address of your computer is in the 192.168.0.x subnet, your DVG-1120M is properly connected.  Proceed to the next step.

  • If the IP address of your computer is not in the 192.168.0.x subnet, your DVG-1120M is not properly connected.  Verify all connections.  This should fix the problem.  If the issue is still not resolved, perform a manual factory reset on the DVG-1120M unit following the instructions in the D-Link documentation.

2.)  Start Internet Explorer and go to the following URL: http://192.168.0.1

3.)  Click "Login to the Web-Based Management Module".  This will prompt you for a user name and password.

4.)  Type admin in the "Username" and "Password" text boxes and then click O.K.

5.)  Using Windows Explorer, go to the folder where the DlinkTftpServer.exe, 1120S_promcode_b09.bin, and 1120S_runtime_s08.tfp files are located, and then start DlinkTftpServer.exe.

6.)  Note:  If you are running a firewall, you may need to either disable it or add the DlinkTftpServer.exe program to the Exceptions list.

7.)  Switch back to the Administration web page.  In the left-hand navigation pane, click "Firmware Update".

8.)  In the 'TFTP Server Address" text boxes, type the IP address of your computer (as shown in Step 1).

9.)  In the "Firmware Update" drop-down list, select "Enabled".

10.)  In the "File Name" text box, type 1120S_promcode_b09.bin and then click "Save".  This will apply the firmware update.  If you are impatient, you can view the Status display in the DlinkTftpServer.exe application to confirm that the upgrade is in progress.

11.)  After the firmware update is applied, click "Save Changes and Reboot System Now" and then click "Save".  The DVG-1120S (yes, it's now a DVG-1120S) will make an audible clicking sound and it will then reboot.

12.)  Close Internet Explorer and the DlinkTftpServer.exe program.

Confirm Upgrade Success

1.)  Go to a command prompt and type the following command: ipconfig /all

  • If the IP address of your computer is in the 192.168.0.x subnet, your DVG-1120S is properly connected.  Proceed to the next step.

  • If the IP address of your computer is not in the 192.168.0.x subnet, your DVG-1120M is not properly connected.  Verify all connections.  This should fix the problem.  If the issue is still not resolved, perform a manual factory reset on the DVG-1120M unit following the instructions in the D-Link documentation.

2.)  Start Internet Explorer and go to the following URL: http://192.168.0.1

3.)  Click "Login to the Web-Based Management Module".  This will prompt you for a username and password.

4.)  Type admin in the "Username" and "Password" text boxes, and then click OK.

5.)  In the "Device Information" window, confirm that 0.00-B09 is displayed in the "Boot PROM Version" field and 0.0-S08 is displayed in the "Firmware Version" field.  If you see different values, you did not successfully unlock your DVG-1120M.

Factory Reset

Now that your device is a DVG-1120S, you'll need to load the correct default settings.  Otherwise, the old DVG-1120M default settings are maintained and they will cause you no end of trouble.

To perform a factory reset:

1.)  On the left-hand navigation bar, click "Factory Reset".

2.)  Click the "Reset to Factory Default" button and confirm that you want to perform a factory reset.

Secure the DVG-1120S

While you are not required to do so, it is a good idea to secure your DVG-1120S with a strong password.  After all, it will probably be in front of your entire network!  To change the password, follow the procedure below:

1.)  Log back on to the DVG-1120S.

2.)  Click "Administration Management".

3.)  In the "Old Password" text box, type: admin

4.)  In the "New Password" text box, type a strong password.  I recommend using passwords of at least ten characters in length that are a non-obvious combination of letters, numbers, and symbols (sorry, your phone number is not a strong password).

5.)  In the "Confirm New Password" text box, retype the password you typed in the "New Password" text box.

6.)  Click "Save".  The dialog box will refresh but you will not see any visible confirmation of the password change.

7.)  In the left-hand navigation pane, click "Save and Restart System".

8.)  Click the "Yes" radio button to save the settings and then click "Restart".  The DVG-1120S will restart and you will hear the familiar audible click.

TCP/IP Configuration

The DVG-1120S is designed to connect directly to your cable or DSL modem and act as the gateway device for your network.

It does not work correctly unless it is assigned an Internet IP address so you really do need to put it directly on the Internet (outside the firewall).  You might also need to put your cable or DSL modem into "bridge mode" in order to get everything working.

  • If you have a static, BOOTP-assigned, or PPPoE-assigned IP address on the Internet, click "Config IP" in the left-hand navigation pane.  You can then click "Config WAN IP Address" to update this information.

  • If you have a DHCP-assigned IP address on the Internet, do not change the default settings.  This is the default.

By default, the DVG-1120S uses the 192.168.0.x subnet for your home network.

If you are not familiar with TCP/IP subnetting and RFC 1918, changing this value is not advised.  However, you can do so on the "Config LAN IP Address" menu.  Don't forget to update the DHCP scope as well!  You can do this on the "DHCP Configuration" menu.

Configuring Free World Dialup Server Information

To configure your DVG-1120S to connect to Free World Dialup servers, click "SIP Configuration" on the left-hand navigation pane, and then click "Server".

1.)  From the "Server FOQDN" drop-down list, select "Enabled".

2.)  In the "Domain Name" text box, type: fwd pulver.com

3.)  In the "Port" text box, type 5060 (this is the default, so do not change it if already displayed).

4.)  In the "Service Domain" text box, type: fwd.pulver.com

5.)  From the "URL Format" drop-down list, select SIP-URL (this is the default, so do not change it if already displayed).

6.)  From the "User Parameter Phone" drop-down list, select "Enabled".

7.)  From the "Timer T2" drop-down list, select 4.

8.)  In the "Register Expiration" text box, type 3600 (this is the default, so do not change it if already displayed).

9.)  In the "Session Expires" text box, type 180 (this is the default, so do not change it if already displayed).

10.)  In the "Min-SE" text box, type 180 (this is the default, so do not change it if already displayed).

11.)  From the "Session Expires Refresher" drop-down list, select uac.

12.)  Scroll to the bottom and click "Save".

13.)  Select the "Continue and Restart Later" radio button and then click "Save".

Configuring Free World Dialup User Agent Information

To configure your DVG-1120S with your Free World Dialup phone number, click "SIP Configuration" on the left-hand navigation pane and then click "User Agent".

1.)  From the "Same Phone Number" drop-down list, select "Enabled".

2.)  Do not change the default value of 1 on the "Index" drop-down list.

3.)  In the "Phone Number" text box, type your Free World Dialup phone number (for example, 55555).

4.)  In the "Display Name" text box, type the Caller ID name you want to be displayed when you call someone (for example, Almon Strowger).

5.)  Do not change the default value of "Yes" on the "Caller ID Delivery" drop-down list.

6.)  Do not change the default value of "Disabled" on the "Display CID" drop-down list.

7.)  In the "User Agent Port" text box, type 5060 (this is the default value, so do not change it if already displayed).

8.)  In the "Authentication Username" text box, type your Free World Dialup phone number (for example, 55555).

9.)  In the "Authentication Password" and "Confirm Password" text boxes, type your Free World Dialup password.

10.)  Scroll to the bottom and click "Save".

11.)  Select the "Save Changes and Reboot System Now" radio button and then click "Save".

Connect DVG-1120S

Now that your DVG-1120S is configured, connect it to the Internet according to the documentation that is included.

If you did everything correctly, the Status light will be solid green after the unit boots and you'll hear a dial tone when you pick up.

You should be able to place and receive calls using Free World Dialup and connect to the Internet via the DVG-1120S.

Tips and Tricks

  • The DVG-1120S does not support STUN.  It must have its own externally routable Internet IP address.  If this configuration won't work for you, then you should not buy the DVG-1120S.

  • You can use the DVG-1120S as a NAT router, although it provides only basic functionality.  UPNP is not supported and you can only forward five static ports.  If you use this unit as the primary gateway for your home network, you're probably not a power user.

  • For some reason, you need to dial ***1-800/1-888 etc. instead of *1-800/1-888 etc. when placing toll-free calls via Free World Dialup.  This condition is unique to the DVG-1120S and I have not heard of any other SIP adapters where this is necessary.

  • Don't put your unit into "bridge mode."  This doesn't appear to do anything except lock you out of the configuration menus, which is a real hassle when you want to change something.
  • The settings documented above are not the only ones that work correctly with Free World Dialup.  However, they are the closest working settings to the default settings.  If you're feeling adventurous (and more importantly, if you know what you're doing), you can fine tune the settings to better match your preferences.

Acknowledgments

If Sigmaz hadn't been curious and wondered what happens when you flash an AT&T CallVantage adapter with Swedish D-Link firmware, this hack wouldn't be possible.

He figured it out.  All I did was write an article.

Looking Ahead

The rapid pace of change in the telecommunications industry, even over the past five years, has been astounding.

Of course, so has the erosion in our civil liberties.

Lately, law-breaking "law enforcement" and so-called "intelligence" agencies have been heavily lobbying Congress to "update and modernize" wiretap laws they have chosen to ignore in the meantime.

Inconveniences such as the Fourth Amendment are awfully unfashionable since September 11th, which, of course, "changed everything" according to the simplistic braying of mindless politicians.

Including, it would seem, the plain language of the U.S. Constitution - but that's a subject for a future column...
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