Datacom > Modems & CSUs

DDS (Digital Data Service) is an AT&T® service that transmits data digitally over dedicated leased lines. DDS lines use four wires, and support speeds up to 56 kbps; however, DDS is actually a 64-kbps circuit with 8 kbps being used for signaling. You can also get 64-kbps (ClearChannel™) service. Since the transmission is digital, no modems are needed. Dedicated digital lines are ideal for point-to-point links in wide-area networks.

T1 is a dedicated transmission line operating at 1.544 Mbps. It’s comprised of 24 DSOs, each supporting speeds of 64 kbps. The user sends data at N x 56 or N x 64 over T1 circuits. T1 operates over twisted-pair cable and is suitable for voice, data, and image transmissions on long-distance networks.

Security modems typically offer four options for levels of security:
• No security
• Password
• Password with callback
• Password with callback and second-level password

Auto callback enables an answering modem to dial a prestored callback number after answering a call.

When configured for auto callback security, modems like the Series II Modems provide secure and cost-effective corporate LAN access for both travelers and telecommuters. Unauthorized connections are prevented by invalid passwords.

Callback numbers minimize toll charges via the following procedure: When called, the security modem will answer and, after a slight delay, respond with a prompt that requests entry of your modem’s login password. Once you’ve typed it in correctly and hit the return key, the security modem can either allow the user through or disconnect and dial back the prestored number.

The security modem gives you several attempts at each prompt to provide correct information—incorrect entries result in a password retry. If the requested information isn’t provided within a set amount of time, your call is disconnected.

Depending on what security level your particular modem is configured for, you may or may not be asked to provide more password information upon callback.

If the second-level password clearance is required, then the security modem responds with another request for your modem’s login password when your modem answers the callback. After you enter the password, the security modem should respond with an acknowledgement of connection.

This acknowledgement tells you that the modems are now in Data Mode, your reversal of phone charges is complete, and you are ready to communicate with the host computer.

Is your company refraining from connecting to the Internet? If so, you’re not alone. It’s the fear of being successfully hacked that’s keeping many companies and their employees off the Internet. In fact, according to Infosecurity News, over 25% of all companies polled responded that hackers have tried to gain unauthorized access from outside the corporate network.

What else keeps companies disconnected? There’s a mystique to being hacked. It’s the new crime, it’s the hottest news. And all this hype, say the media watchers and technical experts, is keeping companies off the Internet.

Why the mystique? Many people, including company executives, lack a fundamental understanding of technology. Mix this with the complexities of network security issues and you can see why many companies haven’t ventured onto the Information Superhighway. What you don’t know, reason many companies, can hurt you.

On the other hand, there are many companies with executives who have “Teflon® sensibilities.“ Media hype doesn’t stick to them. Unfortunately, neither does the advice of company network administrators who want network security problems addressed. These companies go about their connected-to-the-Net business until the inevitable compromise in security happens. And when something valuable is swiped, the executives worry.

“We’ve taken steps to make sure something like this never happens again!“ is the boilerplate reaction. Otherwise, they say, heads will roll. For companies that have been hacked, the cost of information security now equals the cost of the incident plus the cost of countermeasures.

A network, as it turns out, is only as secure as the people who run it, use it, and fund its protection. Industry insiders believe overall spending on information security will increase dramatically.

So protect yourself from hackers while getting the Internet access you need. For answers to your network security questions, call Black Box Technical Support today.