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Archive for the ‘Communications’ Category

If you have done any research into the confusing world of long distance telephone rates, you have discovered that conventional long distance is expensive compared to almost any of the alternatives. This is especially true when you factor in, the extra fees and taxes added on by governments.

Conventional phone companies rely on people being either uninformed or unmotivated to check out the alternatives. Usually they bundle long distance with local services so you are never quite sure how much your long distance service is costing.

For instance, many consumers sign up for a local plan that includes unlimited long distance calling. They usually pay between $50 and $70 for this package. But they could get the same level of service for much less money by staying with a $20-$30/month local package and using a dial around plan that charges only 1.9 cents/minute for calls to the USA and Canada.

**Phone Cards – a solution with serious limitations**

One alternative to conventional long distance service is to purchase a prepaid phone card. These cards are often purchased online. After signing up you are sent an account number and PIN which allow you to access the long distance system.

Having a phone card lets you place long distance calls by calling a toll free access number, entering your account information, and then dialing the number you want to call.

Some of the features and shortcomings of phone cards are as follows:

– Phone cards are often country or region specific. It is difficult to find one card that gives you good rates to multiple countries or regions.

– They are good for short term situations like traveling, or for occasional use.

– Calling can be cumbersome unless you can find a “PIN-less” phone card.

– Charges can be higher than expected because of hidden fees and taxes.

– Calls can be more expensive because of longer call duration rounding intervals. A 6.5 minute call will be billed as 7 minutes if a 1-minute rounding interval is used. But it will be billed as 9 minutes if they use a 3-minute interval.

– Phone cards often have a higher minimum call duration. Some cards charge a minimum of one rounding interval for every call, even if it is not completed.

**Dial Around Plans – a much better alternative**

A much better alternative is what is called a dial around plan. They are called “dial around plans” because you use a local number or toll free number to bypass or “dial around” the conventional phone company. You call the special access number, and once you get a dial tone you dial the area code and number of the party you are calling.

Here are some of the features you can get with a quality dial around plan:

– With good plans you only pay for minutes used. There are no fees, taxes, or hidden charges.

– No monthly minimum charge or account fee.

– Very low long distance rates, including low domestic rates to the USA and Canada.

– Savings are substantial – from 50% to 90% less than conventional long distance.

– Quality plans do not require a caller to enter an account number or PIN when calling from registered numbers. You can register as many as 10 phone numbers with your account.

– Connection quality is comparable to conventional long distance.

– Some plans (higher quality ones) give you free online account management including real time call history. This lets you see the details of every call — the number called, time and date of the call, duration, and cost. Read the rest of this entry »

USB which stands for Universal Serial Bus is a standard for serial communications between computers and other devices. It was first introduced in 1996 and was jointly promoted by Intel, Phillips, US Robotics and Microsoft. USB was developed so that many different types of devices could be accommodated under a single common interface. Due to this capability, nowadays USB devices are the most popular form of plug and play devices. In short, a plug and play device is an external device which we connect to the computer either for data transfer or to provide additional capabilities to the computer. Normally plug and play devices are used along with additional software which acts as a link between the device and the CPU of the computer. This software is called the driver.

Many other standards exist for such connections like PS2, but USB devices provide a distinct advantage over other standards mainly due to two significant reasons.
First, the USB standard allows devices to be connected to the computer without needing to restart the computer. For many previous standards, the computer needed to be restarted before the device could be used. Secondly, the USB device takes its power supply directly from the CPU thus eliminating the need for an external power supply cord. This was only possible due to the fact that USB devices typically consume very little power.
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Radius, Remote Authentication Dial In User Service is a networking concept which is used to provide access to users to services which require logging in, generally with a username and password. This protocol uses servers to store information in the form of a list of user names or passwords. So, when a user wants to log onto for example, the internet, he enters his user name and password and submits them. The data is sent to the RADIUS server and checked against a list of existing users and their respective passwords. If the username and password entered by the user matches the one on the list, then the user is granted access to the internet.

This protocol is widely used by Internet Service Providers (ISPs) as well as large companies, corporations, educational institutions and other organizations to regulate and manage access to the internet as well as to internal networks. Normally these authentications protocol is carried out by devices like the modem, Digital Subscriber Lines (DSLs) automatically.
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Port forwarding, often referred to as .tunnelling. is the forwarding of network ports from one network device to another. This is commonly done using a NAT (network address translation) enabled router or server and another computer within the local network. The main purpose of using port forwarding is to allow hosts outside your local network who doesn.t have their own public IP address access to some services running on machines within your LAN.
Port forwarding is easy to set up on a router since the management interface allows for easy configuration. In some cases this easy configuration feature might be a problem since most routers cannot provide complex customization for port forwarding and other services. In such case a Linux box can do the job. With Linux, port forwarding is configured by adding iptable rules with a DNAT target to the PREROUTING chain and a SNAT target to the POSTROUTING chain. After doing so iptables will use the existent masquerade table to rewrite packages so they will reach the desired host in concordance with the port forwarding rules you provided. This is similar to OSX and BSD, however ipfw is used. In most cases ipfw is already compiled with kernel.
With port forwarding you can use a router to connect to the Internet and also run a web-server or a FTP server on a computer with your LAN. By using port forwarding you can instruct the router to forward all information that comes on a specific net port (such as 80 for the web-server or 21 for the FTP server) to a host within the local network. This means that if an outside host try to make a HTTP request towards the public IP the router has, it will be sent to the machine known to handle such request within the LAN. This is done in a transparent manner, meaning that the network client is not aware of the fact that he is accessing a machine found somewhere in the LAN. Applications of such methods are widely used both in business environments and in small home networks.
With more and more devices in the home needing to be connected to the internet or to each other, the router has become a very popular device worldwide. In such situations port forwarding is used to allow access within the network for applications that require access on a specific port, such as games or multimedia streaming software.eaming softwaR.th port forwarding you can use a router to connect to the Internet and also run a web-server or a FTP server on a computer with your LAN. By using port forwarding you can instruct the router to forward all information that comes on a specific net port (such as 80 for the web-server or 21 for the FTP server) to a host within the local network. This means that if an outside host try to make a HTTP request towards the public IP the router has, it will be sent to the machine known to handle such request within the LAN. This is done in a transparent manner, meaning that the network client is not aware of the fact that he is accessing a machine found somewhere in the LAN. Applications of such methods are widely used both in business environments and in small home networks. Read the rest of this entry »