Reprinted with permission from: www.quickstartvoip.com

In order to use VoIP, both parties need a broadband connection. This is a high-speed Internet, or broadband connection usually provided by a cable or DSL modem. Broadband modems are usually used to connect computers to the Internet, but in the case of VoIP, computers are not necessary.

The simplest form of VoIP is a computer-to-computer voice connection. All that is required for this type of connection is a computer, a headset consisting of earphones and microphone, and VoIP software. Most software packages are free and allow you to connect to any computer running the same software. There is no charge for this type of connection and calls can be made to anywhere in the world.

VoIP software can also be used to connect to land-line phones — that is, phones which are not connected directly to the Internet. This type of call is usually not free but the cost is quite a bit lower than what your telephone company charges. Some VoIP services also allow you to make calls to cellular phones.

The only time that both parties need a particular VoIP software package is when they are making computer-to-computer calls. Parties receiving land-line or cellular calls do not need any extra equipment or software.

VoIP Transmissions

VoIP is based on digital data transmission. The first step in any VoIP call is to convert the analog signal of the human voice into digital data. This is done within an Analog-to-Digital Converter (ADC) that divides an analog signal into discrete steps which are represented by numbers. The next step is to compress the audio data using a codec (enCOder/DECoder) which significantly reduces the amount of digital data while maintaining audio quality.

The compressed digital data can now be sent over the Internet. The data stream must be divided into packets which, besides containing the audio data, also have information concerning their destination and their place in the data stream.

All data that is sent over the Internet is encapsulated in ‘layers’ which aid in its proper delivery. For example, web pages may use the Internet Protocol (IP) network layer to specify destination and origin addresses, the Transmission Control Protocol (TCP) transport layer to create a connection between two computers and the Hyper Text Transfer Protocol (HTTP) as an application layer to allow the Web browser to display the web page correctly.

Most VoIP uses a transport layer called User Datagram Protocol (UDP) which is faster than TCP. A commonly used application layer is Real-time Transmission Protocol (RTP) — originally developed for delivering audio and video over the Internet. RTP provides information about the sequence of the data packets so they can be reconstructed in the correct order at their destination.

RTP also has the ability to drop packets if they do not arrive within a certain amount of time. This is necessary for telephone conversations because if the telephone software waited for every packet of information to arrive before reassembling it there would be unacceptable delays in the audio stream.

Even though some of the packets are dropped, there is usually still enough information to make the conversation legible. The number of packets that will be dropped depends on the speed of your Internet connection in the distance between the two parties.

Once the voice data has arrived at its destination, it is reassembled in the correct order and converted back from digital to analog.

 

With so many companies assembling at the starting line for the race to mobile VOIP world domination, I wonder if we’re seeing a hurry-up-and-wait sort of thing. On the VOIP Service Blog read about mobile VOIP in a nutshell.

I was just thinking about Hictu the other day and I went to have a look at it again. Next thing you know, Luca tells me that they’ve released a new version. Read more here.

I haven’t been using Hictu. There’s been just so many new tools to try. And that’s exactly the issue. In a nutshell, Hictu allows you to see the online presence of contacts on Skype, Gizmo, Abbeyphone, Yahoo, ICQ, MSN, Sitophono, GTalk, AIM, Jabber. They call it a presence dashboard.

This week thevoipgirl.com went down in flames for the first time. I think it was out for a couple of days after I upgraded my WordPress template and then managed to hose my site. After the initial shock, depression set in since I have absolutely NO idea how PHP works. Thankfully the WP template I’m using is superbly supported by its creator and other code wizards. It turned out to be something wonky with the permissions in my index.php and nothing to do with upgrading (greek to me). So, the reason for this post, in a nutshell, is to recommend this highly customizable and well supported template. Check out Semiologic Pro by Denis de Bernardy. Cheers!

Following on Peter Csathy’s post about how he uses SightSpeed for business and personal communication, Andy shares six tips for making video calls. In a nutshell, 1) Get over it, your hairdo’s not that bad 2) Get a hat, 3) Come as you are, be comfortable, 4) Have good lighting, 5) Learn to multitask on camera, 6) Don’t worry about multitasking on camera, it’s not considered rude.

Thanks Andy!

Alec Saunders reviews Talkster, a new service that lets you make inexpensive cell phone calls anywhere in the world, and mobile to IM (Instant Messenger) calls. In Talkster’s words: “There are a couple of cool perks to note with the Talkster service; some of the most important being that there is no subscription to the service to buy (ala Rebtel), there is no software to download (ala Jajah), it works on the cell network you are already used to using (no 3G requirement ala Fring), and it works on the phone you already have today (not just select Java phones). It also works today, with popular IM services MSN, GoogleTalk, and Gizmo Project. In a nutshell, Talkster is the first company to enable mobile-to-PC Voice over IM (VoIM) calls, that works without software, on virtually any phone.” That sounds like something worth trying.

Alec reviews it using his Blackberry and he’s impressed by how easy it is to browse his list of contacts, view their online presence, and make calls. While the service works without software on virutally any phone that supports a browser, in reality only browser-friendly phones need apply. For example, my cell phone has a browser, but the phone itself is of the entry level variety so using the web enabled capabilities is awkward (I find). I’ll be giving Talkster a try with my basic handset and with my husband’s fancy one and I’ll add my comments to the mix.