Thursday, February 15, 2007

What is VoIP? How to use VoIP?

VoIP - Voice Over Internet Protocol - is a very popular buzzword in the Internet world.
VoIP makes communication possible without telephone wires, telephone exchanges and even
without telephones. You can make voice calls free of charge or at a minimal charge over

If VoIP can give the same quality and standard of voice as in normal telephones then
there will not be any need for telephone exchanges any more. People will change to free
or cheaper VoIP alternative sooner or later.

The VoIP service is available in two types. Free service and cheap service. Skype is a
free VoIP service. While services such as Phonewala, HCL, sathyam provide payable VoIP
service. You can download Skype software from .

In payable VoIP service PSTN (Public Switched Telephone Network) plays a part. Therefore
you can call any other phone number through this service. The called person may have
subsribed to the VoIP service or maynot have subscribed to the VoIP service, you can
still make calls to him. Generally the subscribers of the same VoIP service provider can
talk with each other freely. The free VoIP service does not use PSTN. Therefore if you
are using the Free VoIP service then you cannot call other telephone numbers and vice
versa. But you can use the free VoIP service to talk with each other using computers
conencted to the internet.

Ok, now you have decided to try and use VoIP. What are the requirements to use VoIP?
You computer should have sound card, Microphone and speakers. If you have a headphone
then it is better. And then you should have internet connection. Broadband connection is

In 1999, Internet Society, introduced the Session Initiation Protocol (SIP). SIP protocol
is used to find out whether the computer that you want to call is currently connected to
the internet and is available for making a call. Even internet phones use this SIP

Earlier I mentioned that using VoIP you can make free calls between computer to computer. You can also make phone calls from your computer to another phone but at a cheaper rate than the normal phone charges.

If you compare VoIP calls to a normal phone to phone call, it is like comparing the quality of a mobile call and a land line call. Many agree that the quality of a land line to land line call is better than the mobile to mobile call. Similarly the quality of the VoIP calls as compared to phone to phone call is slightly below standard. In VoIP, your voice is converted to digital signals and packed into small data packets and then sent over internet. There is no guarantee that these data packets will be received in the same order in which it was sent. The data packets may get mixed. Therefore in order to get all the data packets and arrange them in order it may take some time and hence there may be delay. This is called 'Jitter'.

If some data packets take too long to arrive then the routers may reject these packets. This will cause 'Packet Loss'. Therefore the speech may be intermittent and sometimes irritable.

And some argue that VoIP is crackable and crackers may evesdrop to these data packets and listen to your conversations. But even normal telephones can be tapped. The VoIP technology is fast evolving and some VoIP providers use Public Key Encryption to encrypt the data packets and hence cannot be cracked.

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