New trend in internet based services

Voice over Internet Protocol (VoIP)
When we speak we generate a 4KHz signal. This signal is digitised and transmitted over the Internet as series of packets. This is the fundamental concept of VoIP and it resembles the existing email system. Chronological development of VoIP technology reduces phone charge dramatically or offers completely free phone call.

Circuit Switching Vs. Packet Switching
Circuit switching is a switching technology that establishes an electrical connection between two devices through one or more intermediate switching nodes. The telephone system uses circuit switching for more than 100 years. When a call is made between two parties, the connection is maintained for the duration of the call. Here the bandwidth is guaranteed, and delay is essentially limited to propagation time.

Packet switching on the other hand is a method of transmitting messages through the data networks, in which long messages are subdivided into small packets. The packets are then transmitted along the different paths or sometimes in a predefined path to the destination. Packet switching is a very efficient method and it lets the network route the packets along the least congested and cheapest lines. In packet switching link is also freed up so other computers share it as well.

VoIP Features
VoIP or net-phone employs packet switching technology to provide the phone service. Currently both hardware and software based services are available for the subscribers. Compare to the software-based services the hardware-based services ensure more clear voice and reliability. To use the hardware-based services, a broadband connection is mandatory. The hardware based services give you two options: adaptors and all-in-one phone units or IP phone.

Adapter: Analog Telephone Adaptor (ATA) allows you to connect a standard phone to your computer or your Internet connection for use with VoIP. The ATA is an analog-to-digital converter. It takes the analog signal from your traditional phone and converts it into digital signal for transmission over the Internet. Service provider such as Vonage provides ATA free of cost with their service. You just plug the phone jack into the ATA, and ready to make VoIP calls. Some ATAs come with additional software for PC based configuration.

IP Phone: IP phone is a specialised phone with a built-in adapter. This device directly connected to the router through RJ-45 ethernet connector has all the essential components to handle the IP call. Soon, Wi-Fi IP phones will be available allowing subscribing callers to make VoIP calls from any Wi-Fi hot spot.

The prime advantage of software based services is the cheap rate or free service facility. Aside from this software based services suffered from poor voice quality although some services offer good quality than cell phone voice. Although no service charge required but you need to collect some basic components such as software, microphone, speakers, sound card, and an internet connection to use this sort of services. Skype is a lucid example of software-based service and it offers PC-to-PC calls for free and PC-to-land line for some charges.

Skype Vs. Vonage
Skype and Vonage both are VoIP services and offer low cost Internet phone service to the people, but their service strategy is quite different. To use skype service you need to download free software from the Skype website. This program is the Skype soft-phone client, which includes an on screen keypad you can use to make calls. This software has good user interface that helps users to add contact, make calls, and import contact information from the address book. If you have no account at the Skype website this program guides you to follow the steps to create user name and password.

The Skype application looks and functions like an Instant Messaging (IM) client. As with an IM client, you can change your online status, look at your contact list and decide whom you want to talk to. In order to use these functions and to make calls, your computer has to be on and connected to the internet, and your Skype application has to be running. Calls to other Skype users are free. To receive incoming calls from traditional phones, you must purchase Skype credit and use the add-on service.

Unlike Skype, Vonage requires additional hardware to use its VoIP service. You sign up for the service at the Vonage website. According to your need Vonage will ship relevant equipments to you.

Skype uses a peer-to-peer network, much like KaZaA, and a proprietary protocol. Vonage, on the other hand, does not use peer-to-peer technology, and it uses Session Initiation Protocol (SIP) to handle the call's data.

The quality of VoIP service is depends on internet connection and the equipment used to make and receive calls. If the data packets are lost or slowed down in transit, the call can become distorted or pieces of the conversation can disappear entirely.

Fax over Internet Protocol (FoIP)
FoIP is a new reality in the Internet world. FoIP follows the same principle as VoIP. Earlier, IP faxing has some limitations such as absence of confirmation beeps and indication of each successful transmission, which are common in the traditional fax system. The latest generation of FoIP systems combines the benefits of traditional faxing and in the same time cut down the cost. The fax information is transmitted as "IP packets" via the internet instead of as analog signals via phone lines.

FoIP allows traditional fax machines to transfer data over the Internet using gateways between phone lines and the Internet. If you want to skip the phone network entirely, you can use an IP fax machine that connects directly to the internet. When you're transmitting a fax between two IP fax machines the transmission cost is the same as for email, and it's faster because transmission is entirely via broadband channels.

The FoIP setup is a lot like the VoIP setup, and you can even send IP faxes using a VoIP server. However, since a fax requires more bandwidth than a voice, a VoIP server doesn't automatically work seamlessly for transmitting faxes. It typically requires some modifications, which you can make by installing a piece of software. Some companies also make servers that are optimised for both VoIP and FoIP applications.

FoIP System
FoIP involves two primary transmission methods such as store-and-forward and real-time.

Store-and-forward: In this scheme, fax information is transferred from fax server to fax server as email attachments, and uses low-level internet protocol like SMTP. In this approach the major setback is that the fax machines are not exchanging information in real-time, so it doesn't consider as a general fax session. For instance, machines can't exchange technical details and the sender does not receive acknowledgement for the received pages.

Real-time: In this scheme, fax information is transferred from fax server to fax serve as IP data packets using a high-level internet protocol such as TCP or UDP. These protocols allow for real-time connections that let the fax machines exchange information along each step of the way. A real-time IP fax feels just like a traditional phone-line fax.

Some possible configurations for the real-time IP faxing system are presented below:

• G3 (traditional) fax machine to G3 fax machine
• Fax-equipped PC to G3 fax machine
• IP fax machine to G3 fax machine
• IP fax machine to IP fax machine

IP addresses are closely associated with these methods. When you're sending a fax from one IP fax machine to another IP fax machine the phone number is immediately converted to the corresponding IP address for the receiving machine. If you're sending a fax from an IP fax machine to a G3 fax machine, the IP fax machine uses the destination phone number to generate the IP address of the fax server located closest to the receiving machine.

The phone-line faxing is based on T.30 protocol and real-time IP faxing is based on T.38 protocol. T.38 converts traditional fax data into an Internet friendly format. It's basically a method of packaging T.30 fax signals and data as IP packets on the sending end and turning these IP packets back into T.30 signals and data on the receiving end.

Despite these problems FoIP considers as a breakthrough technology because it introduced real-time IP faxing. On the other hand, it also an economic way to send long distance faxes.

For further reading please visit these sites: soft-switch.org, webopedia. com, answrs.com, wikipedia.org

The author is a computer engineer.