VOIP for wireless networks

hi this is my first time of writing a blog.
so i would like to start with small intro about me.
I'm pursuing my final year BE CSE in MIT(ANNA UNIVERSITY) its most prestigious college with distinguished set of alumni including former president Dr A.P.J Abdul Kalam.
my area of interest include Wireless communications so i decide to throw light on VOIP STACK.

I hope u would have heard about Skype.Its currently owned by eBay. It is a software application that allows users to make voice calls over the Internet. Calls to other users of the service and, in some countries, to free-of-charge numbers, are free, while calls to other landlines and mobile phones can be made for a fee.As we can see it does require a cost.Hence there must an alternate design which must be made to compensate for extra cost for mobile phones.As India is third largest country in world with max count of cellphones which is to touch approx 20 billion in ther yaer 2015 as according to Qualcomm(an american firm which provides wireless products similar to AT&T BELL LABS) .In long run we have to make sure that even if we make a call from PC the number of landlines is going to be on a decline.As the number of cellphones increases people will automatically shift to GPS and WAP Browsers.We need to ensure how to cut costs on make IPCalls.
before shifting to that we need to get a clear idea of what is VOIP and what are its features etc etc.
VoIP is a revolutionary technology that has the potential to completely rework the world's phone systems. VoIP providers like Vonage have already been around for a while and are growing steadily. Major carriers like AT&T are already setting up VoIP calling plans in several markets around the United States, and the FCC is looking seriously at the potential ramifications of VoIP service

There are three different "flavors" of VoIP service in common use today:

• ATA -- The simplest and most common way is through the use of a device called an ATA (analog telephone adaptor). The 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 data for transmission over the Internet. Providers like Vonage and AT&T CallVantage are bundling ATAs free with their service. You simply crack the ATA out of the box, plug the cable from your phone that would normally go in the wall socket into the ATA, and you're ready to make VoIP calls. Some ATAs may ship with additional software that is loaded onto the host computer to configure it; but in any case, it's a very straightforward setup.

• IP Phones -- These specialized phones look just like normal phones with a handset, cradle and buttons. But instead of having the standard RJ-11 phone connectors, IP phones have an RJ-45 Ethernet connector. IP phones connect directly to your router and have all the hardware and software necessary right onboard to handle the IP call. Wi-Fi phones allow subscribing callers to make VoIP calls from any Wi-Fi hot spot.

• Computer-to-computer -- This is certainly the easiest way to use VoIP. You don't even have to pay for long-distance calls. There are several companies offering free or very low-cost software that you can use for this type of VoIP. All you need is the software, a microphone, speakers, a sound card and an Internet connection, preferably a fast one like you would get through a cable or DSL modem. Except for your normal monthly ISP fee, there is usually no charge for computer-to-computer calls, no matter the distance.

I had copy pasted certain terms.But i will surely explain these terms in subsequents blogs...

Using VOIP:
Chances are good you're already making VoIP calls any time you place a (long-distance call(have i heard it somewhere ya.... in Jab We Met Movie)no wonder Shahid names it "Geet"). Phone companies use VoIP to streamline their networks. By routing thousands of phone calls through a circuit switch and into an IP gateway, they can seriously reduce the bandwidth they're using for the long haul. Once the call is received by a gateway on the other side of the call, it's decompressed, reassembled and routed to a local circuit switch.

Although it will take some time, you can be sure that eventually all of the current circuit-switched networks will be replaced with packet-switching technology (more on packet switching and circuit switching later). IP telephony just makes sense, in terms of both economics and infrastructure requirements. More and more businesses are installing VoIP systems, and the technology will continue to grow in popularity as it makes its way into our homes. Perhaps the biggest draws to VoIP for the home users that are making the switch are price and flexibility.

Most VoIP companies are offering minute-rate plans structured like cell phone bills for as little as $30 per month. On the higher end, some offer unlimited plans for $79. With the elimination of unregulated charges and the suite of free features that are included with these plans, it can be quite a savings. (yaar bahut baat karte ho yaar)=>(yaar you talk a lot).

Most VoIP companies provide the features that normal phone companies charge extra for when they are added to your service plan. VoIP includes:

• Caller ID
• Call waiting
• Call transfer
• Repeat dial
• Return call
• Three-way calling

There are also advanced call-filtering options available from some carriers. These features use caller ID information to allow you make a choice about how calls from a particular number are handled. You can:

• Forward the call to a particular number(hope u would remember what we learnt in MC)(mobile computing course)
  
• Send the call directly to voice mail
• Give the caller a busy signal
• Play a "not-in-service" message
• Send the caller to a funny rejection hotline

With many VoIP services, you can also check voice mail via the Web or attach messages to an e-mail that is sent to your computer or handheld. Not all VoIP services offer all of the features above. Prices and services vary, so if you're interested, it's best to do a little shopping. Now that we've looked at VoIP in a general sense, let's look more closely at the components that make the system work. To understand how VoIP really works and why it's an improvement over the traditional phone system, it helps to first understand how a traditional phone system works
apart from this we have SS7(Standard signaling 7).

In my subsequent blogs i shall tell about the strategy how to develop voip stack for mobile phone.