Talk is Cheap VOIP

We take a brief look at how VoIP works, the government regulations involved, and what you need to use it. We also walk you through the installation and use of a VoIP software called Skype.

Can You Hear Me Now?
VoIP transmits voice wrapped into data packets. A voice call made using VoIP is routed over a packet-switched network, whereas a traditional phone call takes place over a circuit-switch network. This is the essential difference between a VoIP call and a regular call over a land line-every pro and each con of a VoIP service is a result of this. So what is a packet-switched network? When you make a regular phone call, a dedicated connection is made between the two parties involved. This connection is fixed at the two end-points, and has a fixed route over the phone line. The dedicated connection is maintained until the call ends. A packet-switched network, on the other hand, does not establish a fixed route between the two parties. Each packet can take a different route to its destination; packets can even arrive out of order at the destination. A route is taken on the basis of algorithms that balance various network factors such as latency and hops.

To better understand how a VoIP call works, let’s take a look at two parties talking over their PCs. Say Arvind needs to make a call to Swati across the national branches of their business. Let’s assume that both Arvind and Swati have Google Talk installed, and that they are listed in each other’s contact lists. When Arvind clicks on Swati’s username and initiates the call, the software first locates Swati on its network. If Swati answers the call, the software notes her destination address.

When Arvind talks, the voice data involved could be compressed using a proprietary algorithm to facilitate better transfer over the Internet. The compressed voice data is then made into an IP packet-each IP packet is essentially a chunk of voice data wrapped around the destination address. The packet is then sent over the routers, switches, servers and cables that constitute the Internet: they hop between routers and switches, changing paths, perhaps taking a physically longer route to avoid network congestion, thus reducing latency, which you can think of as delay.

Each packet might also be tagged with data other than its destination address-such as the maximum number of hops (the “jumps” it makes along the way) it can take, or how important latency is to that particular packet, and so on. It is important to note that each packet need not arrive at the same order at its destination. When packets do arrive at Swati’s computer, Google Talk handles three things: the shuffling of the packets such that they get into the same order as they were sent from Arvind, the decompression of the packets to get to the raw voice data, and the transmission of the voice data to Swati’s speakers or headset.

Several things happened differently here: no phone number was involved, voice was sent over the Internet rather than a dedicated phone line, and depending upon the quality of the Internet connection between Arvind and Swati, voice packets might have dropped, resulting in bad voice reception.

This last point falls under the purview of Quality of Service (QoS), and is perhaps the largest difference between a VoIP connection and a Plain Old Telephone Service (POTS) one. A POTS service is built upon a circuit-switching network, and has basic QoS guidelines to follow by law. While we might not appreciate the quality over our landlines, it could be worse; indeed, a VoIP connection might or might not ensure a good voice connection. However, some ISPs offer VoIP as part of their service bouquet. These ISPs might ensure a minimal QoS, in which case we recommend you take the service for a test ride before subscribing to an ISP’s VoIP service.

Can Only You Hear Me Now?
Another point of contention over VoIP is that of security. In essence, a VoIP service is based on data packets. When you consider that sniffing of data packets is a very real security problem on the Internet, it’s clear that your voice calls can fall to the same tools and hacks used. The thought of a competitor listening in to your VoIP calls using packet sniffing tools is quite real here. However, two things need to be considered as far as security is concerned. Firstly, if a determined competitor is indeed involved, even a traditional phone is open to wire-tapping. Secondly, it is possible to establish a secure line over the Internet with the help of encryption. Encryption is an essential tool if you do commerce over the Internet, and its efficiency can be, and is, extended to VoIP.

Fortunately, there are many VoIP-encryption products available. Skype has built-in encryption. Phil Zimmermann of Pretty Good Privacy (PGP) fame has recently released a beta tooled dubbed Zfone (www.philzimmermann.com/EN/zfone/ index.html), an open source product for enabling VoIP security. At the time of writing, Zfone is only available for the Linux and Mac platforms, with Windows availability targeted at mid-April 2006. Moreover, VoIP security is a very visible problem-one that companies small and big are aiming to resolve. You can learn more about current and future initiatives at the VoIP Security Alliance-www.voipsa.org.

A final note of caution can be made in regards to fly-by-night VoIP providers. Although you can set up a VoIP service yourself, with the basic amenities available, some ISPs also provide it as part of a data or service package. But as VoIP gains acceptance, small operators are bound to mushroom, and one needs to be chary of subscribing to their services-they might well disappear overnight!

For a business in India, then, there are two options: you can use VoIP to make substantially cheaper international calls, and you can use VoIP to make calls to a national branch. While the former can be either computer-to-computer or computer-to-phone, the latter can only be between two personal computers. Additionally, if your company has a large local network, it can deploy a VoIP solution across it.

The common element here would be a good connection to the Internet. As a rule of thumb, avoid ISPs that connect you via a satellite link-the latencies involved would make for a not-so-great voice connection. Try to stick to providers that connect via undersea cables instead. Some ISPs offer VoIP as separate services; test these out first before subscribing. Also note that some ISPs charge by data traffic, instead of a flat monthly or quarterly rate. For such a service, you are likely to be billed for a voice call, since a voice communication over the Internet essentially involves exchange of data packets.

Dialling Into VoIP
The minimum requirements for making phone calls over the Internet are: a PC at one or both ends, VoIP-enabling software running on the computer(s), a microphone, and speakers or headset. You then install the software at every computer that you need to connect to, and go through the sign-up process for the software. Placing a PC-to-PC call is as simple as double-clicking on a contact’s ID in the software; dialling to an outstation phone line will require you to dial the phone number.

Apart from this simple solution involving your computer, you can also pick up a VoIP-enabled handset to make calls. Such handsets resemble traditional phones, and generally connect to the Internet via Wi-Fi, or even through cable. A handset will support a particular software implementation-for example, Skype is widely supported by such solutions. The handset then effectively replaces your computer/speaker/microphone combination. Moreover, if the handset uses Wi-Fi to connect to the Internet, its usage area is only limited by the Wi-Fi coverage in your company or location.

Some handsets also allow traditional GSM calls to be made-you can switch to VoIP when you are under Wi-Fi coverage, and “fall back” to the cellular network when outside the coverage area-making for a comprehensive and cheap communication solution.