The first thing to know about free VoIP calls is that none of them are actually completely free. Even in the best hypothetical case in which the VoIP provider doesn't charge you at all, remember that you still have to pay for your broadband Internet connection. You must understand that the goal is not to achieve completely free calls to all destinations, but to use the VoIP operator that suits your needs best. Keeping that in mind, you will learn that most VoIP companies will let you talk for free in their own network but also they will charge you for making calls outside their proprietary network. The main way for free VoIP calls companies is to offer free calls inside their own network and also towards other specially selected destinations. Using this tactic users are drawn to make calls to free destinations and afterwards purchase credits to make calls towards paid destinations.
There are several ways used by VoIP companies to lure customers and make a profit in the same time. The great thing about VoIP calls is that they're very cheap, but not completely free, here are some systems used today in the VoIP calls market: If you take Skype for example, one of the most popular VoIP services on the market, you will see that you can initiate conversations with other PC users of Skype free of charge. Of course, this is an advantage for long distance calls, as there is no fee for calls inside the Skype network. But if you want to make calls to regular landlines, you'll have to pay. The subscription fee for calls in North America is $30 per year. It's not a great deal of money but it still isn't free. You can make free phone calls on a PC to PC basis using the Skype software, and the number of users on the Skype network is continuously growing. On the other hand if you want to reach someone that doesn't have a PC or an Internet connection, you'll have to pay the required fees. Another approach to this, could be the way Raketu is seeing things. Raketu is offering free phone calls to landlines in 42 countries and besides that, it also offers live video television. The downside to Raketu's service is that they ask you to pay $9.95 up front in order to use their free services. They say it's used as credit if you happen to call destinations that are not on the free call list, but either way you look at it; it's money that you have to pay to use the service.
If you are in the pursuit of a real cost free VoIP service you can use something like voipCheap that allows you to make free calls to PC's and regular phone lines. It also includes many destinations outside USA and Canada that can be called without paying a cent. The downside is that you have a limited number of 300 minutes that you can use each week, per IP Address. If you talk more than the included 300, you are required to pay for further calls, you are also required to pay for calls outside of the destinations listed on the free call list. To better understand how to make free VoIP calls, let's take a look at how VoIP telephony works. Basically all you need is to setup a VoIP gateway, that's most commonly done by using a PBX. A PBX (Private Branch Exchange) is a device that allows the VoIP provider to purchase as many telephone lines, as the maximum number of simultaneous callers. In general, around 10% of the users will make calls at the same time. This means that the VoIP can purchase fewer telephone lines, instead of buying one for each user. This brings us to the point, configuring a PBX is almost cost free, the actual costs come from the prices collected by the telephone companies for connecting to the PSTN (Public Switched Telephone Network). What VoIP providers do is use PSTN connections for accessing the public land and mobile telephone lines, but at the same time uses the SIP (Session Initiation Protocol) to stream media content such as voice over the Internet. With so many VoIP providers appearing every day the problem of interconnecting, preferably free of charge, with other VoIP providers arises. There are several ways to do this, as some of the existing VoIP providers that use SIP technology have already made peering arrangements to allow users interconnect for free. All you have to do, is use the special prefix code put at your disposal. Although this is not standard procedure, just yet, it's still widely used. The only problem with this is that some devices, such as VoIP phones cannot input the format of the prefix (the prefix usually looks similar to this: number@some_provider.com). As a solution to this, groups like SIP Broker or Voxalot, assign numeric values for your SIP URL, so it can be used on a wider scale of devices.
Although there is no such thing as completely free VoIP telephony, and with some VoIP providers there are some serious hidden costs and restrictions you have to look for, VoIP calls are still very profitable. Knowing that you can make free calls towards destinations in the same VoIP network as you are, and in VoIP networks you have peering with and also towards special destinations selected by your service provider, you can see which combination better suits your needs. If you manage to use services that offer good deals for what you require, you can save up to 98% from your phone bills. This means that you will need to put some time and research into it, but in the end you can achieve almost free calls via the VoIP technology using several and payment methods.
Taken from : http://www.tech-faq.com
