VoIP Tutorial


Voice over IP (VoIP) defines a way to carry voice calls over an IP network including the digitization and packetization of the voice streams. IP Telephony utilizes the VoIP standards to create a telephony system where higher level features such as advanced call routing, voice mail, contact centers, unlimited calling, long distance calling etc., can be utilized.

VoIP and IP telephony are ever more admired by large corporate organizations and consumers. Many people are in impression that Internet Protocol (IP) is limited only as a way to transport data, but that is not actually a true statement. IP is also a protocol tool that simplifies and streamlines a wide range of business applications.

VoIP—or voice over IP—is the basis for the foundation of more advanced unified communications applications—these include:

  • Web and video conferencing. These features help businesses to completely transform the way they do business for their benefit.
  • VoIP technology. This is the technique that carries phone calls over an IP network. It doesn’t matter whether you are on internet or your own internal network. VoIP helps your business to reduce expenses as voice calls travel over the data network rather than the phone company’s network.


Voice over Internet Protocol (VoIP) technology usually works on broadband internet connections VoIP communicates and makes phone calls over established internet connections, similar  with analog telephone lines.  A basic VoIP system makes calls over to another person who is also receiving calls on internet connection.

Interconnected VoIP services also allow you to make and receive calls to and from traditional landline numbers, usually for a service fee. Some VoIP services require a computer or a dedicated VoIP phone, while others allow you to use your landline phone to place VoIP calls through a special adapter.

VoIP is today a very attractive and cheap communication option available in telecom industries.

Today VoIP services gain much popularity and day by day it is increasing drastically offering high voice quality and cheap call rates over basic broadband connections.

As the VoIP penetration to consumers increases, so the potential threats to the users. Apart from the cheap and attractive services by VoIP, it is also vulnerable to many threats, scams, and attacks because VoIP calls now traverse the internet.


In a basic VoIP network setup we have the following important components.


Router’s basic function is routing the data traffic. However, routers allow you also to use your traditional phone to place VoIP calls if you have a special adapter installed on the router device.

They are connected with cable/DSL modem (or any high speed internet connection) and allow you to connect a telephone on them. They need to be configured with an appropriate VoIP provider and service plan, with no special software requirements to interact with the computer. You just have to pick up your phone and dial a number at the dial tone.


Switches act as the channel that forward the incoming data from multiple input sources to the specific output port towards the intended destination. These are used to connect a number of IP phones or analog phones and computer systems for the users as per the numbers required. These switches then forward the data to single destination (to the router usually) which then routes the traffic to the configured destination path and move forward the VoIP call.

 Adapters (USB)

Adapters are used to use traditional phones to place VoIP calls. They usually are in the form of USB adapter connectors that is larger than a typical thumb drive. You can attach an ordinary phone line to the standard jack modular phone provided in that. Once you finish with the connection, you phone will behave like a standard phone service. But actually a Voip software is running at the backend of the system which helps to make a call.

Software-controlled VoIP applications: “softphones”

There are many softphone applications available in the market that help you to place a VoIP call directly from your normal PC with any headset, microphone etc. These applications and services can be provided by telecom providers. With these applications users are allowed to talk to other people using many services (such as voice and video) almost at no cost. A VoIP application based on software instead of hardware is installed on your computer. This is the Softphone. These are quite attractive and cheap as well for the consumer.

Dedicated VoIP phones

There are also dedicated phones available today in the market with several advanced features. VoIP phones are like simple and ordinary phones available for home with cord or without cord/cordless phones. A VoIP phone which has a dedicated connection consists of phone and base station which further connects to the internet or can also operate on local wireless network. Same like VoIP adapters, dedicated Phones can also be offered from voip provider with service plans to work.

Requirements for VoIP and Availability

VoIP services don’t have all the features, functionality and other options equally as with traditional landline services; there are some basic requirements, availability and some possible service limitations of VoIP service compared to traditional landline telephony. Before you opt in to VoIP as a primary means of communication or an enhancement to your current services you need to know the requirements and limitations.


The main and basic requirement for a VoIP system to work is to have basic internet connection through an ISP that allows a VoIP service to actually make the calls or a VoIP service to extend the reach to traditional landlines. But Plain Old Telephone Service doesn’t need any of these services to make the call. It is important to note that Digital Subscriber Line (DSL) internet service uses traditional phone lines for your internet connection; so that your internet with DSL already have telephone service to begin with.

Availability of Power Supply

Power outage is the major threat with the VoIP service as they become unavailable under typical power outage. VoIP devices like computers, routers, adapters etc all rely on power supply to run. So power supply is the most critical resource for VoIP to function properly. If you really don’t want this to happen in case of emergency you can use an uninterruptable power supply (UPS) with a VoIP installation if you are in urgent need of connectivity during power outage or in any emergency.

Connectivity Bandwidth Availability

High-speed internet connection is another important requirement for reliable functionality of VoIP communication. In fact, speed of the internet connectivity may affect your voice quality and many other interruptions you may face while calling. Slow bandwidth may degrade your quality of service. For example if you are trying to make a call and some other person are using a lot of bandwidth like some downloading on the same internet connection, the sound quality of your call will be affected badly.

911 services

911 service is available for many interconnected VoIP and traditional landline services but this is not a service with basic voip (VoIP to VoIP setup). Even if you have interconnected VoIP services, 911 services are not assumed to be present and working. You need to see the terms of service agreement to make sure you have 911 services. There are some tips and some challenges for VoIP services described under the FCC agreement for subscribers.


In this VoIP network architecture setup there are two sites Site A and Site B which are connected by a point to point serial connection.  The two sites are connected by two Cisco 2811 ISR routers. For the LAN connectivity we have used two Cisco 3560 POE switches to connect all local LAN devices such as phones, computers etc.

What should be the output of the architecture?

  • Setup Working PPP WAN between two sites
  • Setup NAT at each site if you need internet access
  • Configure Routers telephony services
  • Setup Configuration of Phones
  • Setup a Site-to-Site Calling


Equipment Used in Architecture

  • 2 – Cisco 2811 Routers w/WIC-1T
  • 2 – Cisco 3560 24port POE
  • 4 – Cisco 7960 IP Phones
  • 4 – Computers


Site Configuration

Site 1


  • LAN IP (data):
  • LAN IP (voice):
  • WAN IP:
  • VLANS: Data-40, Voice-50
  • Phone Ext. – 54001, 54002

Step 1: Configure interface FastEthernet 0/0 and DHCP server  on RouterA (2811 router)

!Configure the FA 0/0 interface


RouterA#configure terminal

RouterA(config)#interface FastEthernet0/0

RouterA(config-if)#ip address

RouterA(config-if)#no shutdown

The DHCP server is needed to provide an IP address and the TFTP server location for each IP phone connected to the network.

! Create DHCP pool named VOICE

RouterA(config)#ip dhcp pool VOICE

! DHCP network 192.168.10 with /24 mask


! #The default router IP address#


! #Mandatory for voip configuration. Option 150 is the server for the phones to boot up

RouterA(dhcp-config)#option 150 ip

After the configuration, wait a moment  and check that ‘IP Phone 1’ has received an IP address.

Step 2: Configure the Call Manager Express telephony service on RouterA

You must now configure the Call Manager Express telephony service on RouterA to enable VoIP on your network.

! #Configuring the router for telephony services#


! #Define the maximum number of directory numbers#


RouterA(config-telephony)#max-dn 5

! #Define the maximum number of phones#

RouterA(config-telephony)#max-ephones 5

! #IP Address source used for the telephony service

RouterA(config-telephony)#ip source-address port 2000

! ! #Automatically assigning ext numbers to buttons#

RouterA(config-telephony)#auto assign 4 to 6

RouterA(config-telephony)#auto assign 1 to 5


Step 3: Configure a voice vlan on SwitchA

Apply the following configuration on SwitchA interfaces.

This configuration will separate voice and data traffic in different vlans on SwitchA.

Data packets will be carried on the access vlan.

! #Configure interface range#

SwitchA(config)#interface range fa0/1 – 5

SwitchA(config-if-range)#switchport mode access

! #Define the VLAN on which voice packets will be handled#

SwitchA(config-if-range)#switchport voice vlan 50

Step 4: Configure the phone directory for IP Phone 1

Although ‘IP Phone 1’ is already connected to SwitchA, it needs additional configuration before being able to communicate. You need to configure RouterA CME to assign a phone number to this IP phone.

! #Defining the first directory entry#

RouterA(config)#ephone-dn 1

! #Assign the phone number to this entry#

RouterA(config-ephone-dn)#number 54001

Step 5: Verify the Configuration

Ensure that the IP Phone receives an IP Address and the phone number 54001 from RouterA  (this can take a short while).

Step6: Configure the phone directory for IP Phone 2

Connect IP Phone 2 to SwitchA and power the phone ON using the power adapter.

!#Defining the second directory entry#

RouterA(config)#ephone-dn 2

! #Assign a phone number to this entry#

RouterA(config-ephone-dn)#number 54002

Task 7: Verify the configuration

Ensure that the IP Phone 2 receives an IP Address and the phone number 54002 from RouterA  (this can take a short while). Same procedure as task n°5.

Dial 54001 and check if IP phone 1 correctly receives the call.


Site 2

  • LAN IP (data):
  • LAN IP (voice):
  • WAN IP:
  • VLANS – Data-40, Voice-50
  • Phone Ext. 2000


Similar configuration as Site 1


In Review – Sylvania Netbook

You may never have heard of Sylvania products before, but chances are you already have one in your home. Sylvania is a branch of a Japanese electronics corporation that specializes in making consumer-grade electronics for other corporations such as Toshiba and Kodak. The parent company, Funai, decided to try their hand with branding netbooks they were creating as “Sylvania netbooks” and marketing them directly to consumers themselves. While the brand may not be the most stylish around, Sylvania is a trusted leader in manufacturing and their computers are also a testament to their quality.

The only entry Sylvania has made into the netbook market is with the “Magnic Plus.” The netbook itself isn’t anything spectacular performance wise as it only has 1GB of RAM and the standard 1.6GHZ Intel Atom processor. What makes it stand out from the crowd though is the price point that the netbook is sold at. Because Sylvania typically makes things to wholesale to other manufacturers, their products are much cheaper than the name brand netbooks already available on the market. That means that you can snag one of these bad boys for just a fraction of the cost of other big name netbooks like the ASUS EEE PC or Dell Mini.

Speaking of cheaply priced netbooks, there has been a growing trend among consumers looking for netbooks under 100 dollars. Unfortunately, 100 is just too low of a price to ask for all of the technology available within a netbook. While companies are still making a profit each time they sell a netbook to someone, many times the profit margins are so slim that they hardly make a dent in the company’s total earnings. Many companies branched out into the netbook market to expand their product lineups and expand their working brand. With so much competition in the laptop and desktop world, being able to make a mark in a relatively new computing market was important to manufacturers, causing them to drop their prices on their netbooks.

By far the best deal you can nab on a cheap netbook is the Sylvania listed above. It contains all of the same parts and features that mainstream netbooks have and comes at a fraction of the price. And with technology advancing so quickly, prices continue to drop on products like the Magni-Plus and are forcing the mainstream competition to drop their prices farther as well. Now is definitely the time to buy a netbook if you’re new to the market!

Choosing the Right 7 Inch Tablet PC For You

When you are looking for the right 7 inch tablet pc that will suit your needs there are various things to consider. Things like price, specifications and availability always come into mind and are the first things to consider. If you are one of the many people who would love to own a tablet but can’t decide as to what particular model to get then here’s a simple guide to help you.

Unlike Apple’s iPad that has a relatively uniform price; the best 7 inch tablet pc models are priced at both ends of the spectrum. You have models that come in very cheap while others are priced as high as the iPad. Which model should you get then? The best decision to make is to work on your own budget. Think about how much you are willing to spend on a tablet then go ahead and find specific models within your budget range.

Dual Core or Single Core
The older 7 inch tablet pc models use a single core while the newer ones released this year come with dual core processors. The difference between the two is that you get more power with dual core processors. If you intend to use your tablet to enjoy the latest games then the dual core models are a must, otherwise stick with the single core.

3G or not 3G? That is the question
Tablet manufacturers often release different versions of a particular model. One version might only come with Wi-Fi while another comes with Wi-Fi plus 3G. With a Wi-Fi only model you can only go online when you are connected to a wireless hotspot while the 3G model makes use of your wireless carriers 3G network. If you intend to stay connected constantly the the 3G model will suit you better however be prepared to pay data charges from your chosen carrier.

Operating System
The most popular platform for 7 inch models today is Google’s Android platform. Try to choose a mini pc tablet running either Android 2.3 Gingerbread or Android 3.0 Honeycomb for Android based tablets. Research In Motion also has a new tablet out in the market which is called the BlackBerry Playbook that runs on BlackBerry tablet OS based on QNX.

Wireless Access Point Reviews – How and Why Standards Matter

If you plan to DIY a wireless local area network (WLAN), you may want to know what a wireless access point is and what those terms like 802.11a/b/g/n refer to. After all, it is the most important device in a WLAN, and a bad choice would affect the overall performance. What follows are some wireless access point reviews that may help you.

What is a Wireless Access Point?

It refers to the device, which acts as the centralized receiver and sender of wireless signals in a local area network. In other words, all other wireless devices talk with the access point only. If two other wireless devices want to communicate with each other, they will have to use an access point as a medium. Thus, the first thing to consider is to have Linksys wireless access point setup properly, wherein Linksys is one of the common brand of WAP devices.

When the number of devices increases, the overall bandwidth demand will also increase. The access point, because of its capacity limit, will become the bottleneck of your WLAN.

In addition, since all the traffic goes through the access point, and a malicious attacker can easily capture wireless packets, security of a WLAN relies greatly on the encryption strategy of the access point.

What Does 802.11a/b/g/b Mean?

802.11a/b/g/n refers to different industrial wireless standards. 802.11g is the most widely adopted standard now, and most of the wireless devices you see are 802.11g compatible. 802.11n is the newest wireless standard, which provides higher speed limit and wider signal coverage. 802.11n is a promising standard and is likely to be supported by most new wireless devices. 802.11a/b are relatively old standards and not used very often.

How Does the Standards Affect a Wireless Access Point?

As one of the wireless devices, an access point is greatly defined by the standard it implements. Different standards lead to different frequencies of channels, transfer rate limit and security measures. The 802.11g access points use the 2.4GHz channel and have a transfer rate limit of 54Mbps. The wide spread of 802.11g standards is now a problem because it leads to high probability of interference between wireless devices such as wireless keyboards and wireless adapters.

The 802.11n access points can use either the 2.4GHz or the 5.4GHz channel and has a transfer rate limit of 540Mbps. The 5.4GHz channel is cleaner and fewer conflicts will happen. The 540Mbps transfer rate limit makes it comparable with the speed of a wired local network. Thus, having a wireless router booster as well can make the connection more faster.

The above wireless access point reviews are mainly centered on the importance of standards. When you are purchasing your own WAP, you should look for as many specific reviews on specific products as possible.

Types Of Wireless Speaker Adapters

If you’re setting up a theater room or a home theater, and you buy wireless speakers for this purpose, it is recommended that you buy a wireless speaker adapter. For people who live in houses that were built many years ago, wires and cables are certainly of interest. Installing cables through walls and wood floors are very uncomfortable, and it’ll look like a big web. Thus, the wireless speakers for tv were invented to relieve this discomfort, even if you live in a house built over a century ago.

Now, after installing the speakers, all you need is to install adapters. These devices are designed specifically to make them work, even with the speakers not only the old and new. They assist in traffic than perfect sound, even if other wireless objects are present in your home. These adapters can run on electricity from its main source of domestic appliances, or may even be forced to work for the same audio device that you listen. But nevertheless, they are clutter free; you do not have to worry about wires and cables any more.

There is a difference between the wireless adapters that have a Bluetooth adapter and a standard set of wireless stereo speakers. Bluetooth adapters, as the name implies, use Bluetooth technology to transit the audio from MP3 players or other audio device for receivers, whether speakers or headphones. Speaker of the adapters is almost no interference of sound, which makes the sound quality above all. This type of adapter is usually directly related to the audio devices. Standard adapters are equipped with cable outlets, which in turn are connected to the outlet of the speaker. They run on electricity and come in nine models typically volts. Once you plug it in, you’ll see a symbol flashes on the screen, indicating that the adapter has successfully connected.

The last thing on speaker adapters is that when you find these adapters, you must make sure that you choose the one that is compatible with your audio device and speaker. If you want to use these wireless speakers in your office, it is best to use a Bluetooth adapter for the speakers and portable music players.

Product Review WordPress Theme Review

There is a relatively new wordpress theme in town, called Product Review WordPress Theme. Well actually is not that new. Its almost one year old, and its developed by a company called cheapinternetmarketing. This company develops also some other nice marketing scripts and tools, such as Product Launch WordPress Theme, Viral Referrer and Squeeze Boss Theme.

I have bought the theme and installed it on one of my blogs. Looks really nice and professional. When doing product reviews, it is a must that you look credible and professional in order to convince the potential customer and click the buy button. Ofcourse, your product reviews must first be honest, accurate and reliable.

The theme works great for sites that review several products in a single niche. Also, it can be used on a site which has product reviews for several niches which are categorized inside the theme. Overall it is a great theme and gives you the ability to focus on writing and keyword research instead of messing around with complicated technical issues for setting up a nice looking theme.

I was reading the warriorforum before buying the theme, and there were some initial complaints about bugs etc. However, the developer has fixed all of them and the theme looks like its matured now. So, go ahead and buy if you want a good looking, professional, and flexible review theme for wordpress.