By Michael Lemm

Don’t be confused about the difference between DS3 and T3 circuits. These terms are really synonymous. Instead you should focus on what they can do for you…and the best scenarios for application.

Digital Signal (DS) is a system of classifying digital circuits according to the rate and format of the signal (DS) and the equipment providing the signals (T). DS and T designations have come to be used synonymously so that DS1 implies T1, and DS3 implies T3.

A DS3 line (also known as a T-3) is an ultra high-speed connection capable of transmitting data at rates up to 45 Mbps. A DS3 line is equal to approximately 672 regular voice-grade telephone lines, which is fast enough to transmit full-motion, real-time video, and very large databases over a busy network. A DS3 line is typically installed as a major networking artery for large corporations and universities with high-volume network traffic. Other example applications include large call centers, enterprise wide VoIP and IP PBX systems, Internet service providers, research labs, video conference centers and software development companies. A DS3 is the second fastest, non optical connection offered in North America. A DS3 line is comprised of 28 T1 lines, each operating at total signaling rate of 1.544 Mbps.

DS3 circuits provide businesses and Internet Service Providers (ISPs) with up to 45 Mb/s of dedicated Internet connectivity. This is an ideal solution for users who have outgrown their T1 connections and are in search of unlimited, high-capacity access. A DS3 line actually consists of 672 individual channels, each of which supports 64 Kb/s. DS3 lines are extremely high bandwidth connections into a carrier’s backbone. They typically include SLAs (Service Level Agreements) that guarantee uptime and performance.

The DS3 signal itself is composed of 28 DS1 signals and is constructed using a two-step multiplexing process. First, the 28 DS1 signals are multiplexed into seven DS2 signals. Second, the seven DS2 signals are multiplexed into one DS3 signal. Each multiplexing step uses bit stuffing to handle the different input frequencies. Overhead bits provide alignment, error checking, in-band communications, and bit stuffing control information.

Line rate: 44,736,000 b/s
Signals: 7 DS2 signals = 28 DS1 signals
Overhead bits:
56 bits total/frame
F-bits (framing) 28 bits/
M-bits (multiframing) 3 bits/
C-bits (stuffing) 21 bits
X-bits (message) 2 bits/
P-bits (parity) 2 bits/
Data bits between overhead bits 84

A DS3 connection is comprised up of two monthly charges: the local loop and the port charge. The local loop charge is the cost of the circuit provided by the Local Exchange Carrier (LEC) that allows DS3 access into the carrier’s network. The loop charge is based on the distance from the customer’s location to the edge of the carrier’s network; the farther the customer is from the network, the more the loop will cost. Nearly every carrier prices loops differently so it is in your best interest to price DS3 service with several providers to ensure that you get the best deal.

DS Internet Access is the ideal solution for businesses that require high-bandwidth access at a reduced price. Whether you host high-traffic Web sites, support Web hosting or need high-capacity bandwidth on an as-needed basis, there’s a level of DS3 service (Full or fractional) that will meet your needs. Fractional to full DS3 or T3 circuits run from speeds of 3 Mbps up to 45 Mbps.

For customers that require more bandwidth than a T1 line can provide but do not yet require the capacity of a full DS3 line, a fractional DS3 connection is the ideal solution. A fractional DS3 is similar to a full DS(T)3, only with some of the channels turned off. This reduces the total monthly cost and provides additional capacity that can be turned up in a matter of days. Unfortunately, the DS3 (T) loop is still required for this service.

If a full DS3 line is more bandwidth that you really need, it is also possible to get Fractional DS3, which gives you a portion of full DS3 bandwidth at a lower cost. Of course, DS3 is also available in multiples to increase bandwidth, similar to bonded T1 service.

DS3 service can be deployed for a wide verity of applications. The most common uses are DS3 point-to-point, DS3 internet, DS3 frame relay, DS3 voice and DS3 VPN. The pricing for these connections varies widely depending on the carrier, location of service and the application for which the connection is being used. Visit DS3 Bandwidth to obtain current “real time” rate quotes for your location.

By Nathan Smith

Try VoIP Before Buying

So you like the concept of ‘cutting’ your phone service in favour of VoIP but are hesitant to take the plunge and abandon your ‘Landline’ without trying it out for yourself first. Perhaps the advertised features and rates all sound a little ‘too-good-to-be-true’. The terrific news is that you can make VoIP calls using your computer to virtually any telephone or computer in the world with little more than an Internet connection and a headset.

‘Free VoIP’ Using a Softphone

Firstly, let’s look at the ‘Free’ way of taking VoIP for a test drive. So what’s a ‘Softphone’ I hear you ask? A ‘Softphone’ is merely a ‘Software’ ‘Phone‘ that enables you to use your computer like you would a telephone. Softphones are programs that generally resemble the keypad on a telephone and function in much the same way.

Softphones enable you to call other ‘Internet-connected’ devices or softphones for free (Free PC to PC VoIP), or conventional telephones for a small fee (PC to Phone VoIP). The reason that ‘PC to Phone VoIP’ calls (i.e., to conventional phones) are not free is that in order to call normal telephones, your call needs to route partially through the heavily regulated, heavily taxed Public Switched Telephone Network (PSTN). As long as the person you’re calling is also connected to the Internet, you can talk for as long as you like across the neighborhood or on the other side of the world for free. Furthermore with PC to PC VoIP, there aren’t any contracts to sign or commitments to make. Just download the softphone, and start talking.

PC to Phone VoIP

If you’d like to try VoIP by calling conventional telephones, consider PC to Phone VoIP. Depending on the Service Provider you choose and the destination country you’re calling, the cost could be as little as just a few cents per minute. As long as you purchase ‘pre-paid’ calling credit, you won’t need to enter into a contract of any kind and can use that credit to call any telephone around the world. The smallest denomination of prepaid calling credit usually begins at $10 USD. However, at just a few pennies per minute this easily equates to over 5 hours of talk time. As an added bonus, some PC to Phone service providers also enable free PC to PC VoIP calls using the same softphone as that used for their PC to Phone VoIP calls. That way, you can call a conventional phone using PC to Phone, then arrange to meet the person you’re calling online (PC to PC VoIP) to continue talking for as long as you like, free of charge.

So try VoIP for yourself before you buy. You’ll get an idea of the exceptional call quality and fantastic call rates available before entering into a contract that replaces your landline.

By Mansi Aggarwal

Revolutionizing the world of telephony, VoIP has become one of the fastest growing technologies of today. It has quickly gobbled up the market for the traditional and well established tools for communicating over large distances, by making them look antiquated and expensive.

Voice over Internet Protocol (VoIP) is basically a process which converts your voice into digital signals that travel over internet. Its most prominent feature is its affordability. With VoIP you can make long distance calls at a fraction of cost that you used to pay to your telephone companies. It is primarily because of the fact that transferring digital signals over internet is quite cheaper than transferring analog signals over the traditional telephone lines.

However, nowadays VoIP is in the news not for the great savings in long distance calls that it offers but for the security concerns attached to it. As VoIP runs through internet, the information exchanged can be intercepted by anyone at any time. Moreover, because of its popularity VoIP has become a soft target for the hackers. In the absence of a strong firewall system, hackers may capture sensitive information such as credit card number and bank details. They can even launch denial of service attacks and shut down a voice conversation, or send spam or virus over the internet to disrupt the services. Another vulnerability that the IT sector is worried about the hacking of VoIP networks for making free calls. According to industry sources, a new generation of “phreakers” may be able to manipulate the data switched through a hybrid TDM-VoIP network which will allow them to exploit the billing system to make free calls. Another menace that is plaguing the VoIP networks is ‘caller-id spoofing’. There are some hacking websites that allow people to control the phone number that appears on the receiver’s caller-id display. Moreover, they can modify their voice with the help of voice modification software. Thus, they have become a useful tool for private investigators and pranksters.

VoIP service providers are now trying to secure their customers from these threats through the tunneling and encryption processes. These techniques prevent the hackers from capturing the information packets as they pass through the internet. Most of the service providers are using Layer 2 tunneling and an encryption method called Secure Sockets Layer (SSL) to prevent anyone from getting the confidential information. However, despite of all these possible threats the IT segment is still enthusiastic about the cost savings and the added functionality that VoIP offers to their business. Most of them consider VoIP as a reliable and robust system and the security concerns not so serious to hamper the progress of VoIP.

Thus, although the attacks on the VoIP systems are at a nascent stage but they may gain teeth and hit the consumers sharply as the hackers become aware of the details of this service. Thus, it is necessary for the concerned authorities to understand the criticality of the situation and be ready to take the necessary preventive measures to prevent any major impact of these threats on VoIP in future.