VoIP is an abbreviation for Voice Over IP, ie. the transmission of voice over the Internet. A VoIP service in essence, consists of a computer that can make phone calls to anywhere in the world. It may be PC to PC or PC to phone, landline or mobile. The voice signals are converted into data packets that travel over the Internet using a VoIP platform, and then converted back into the recipient.

Using VoIP requires specific modules in the router or switch that have the digital processors (DSPs). In this case, the router or switch are called as voice gateways.

The VoIP (Voice over IP) enables the Cisco gateway (router or switch) to carry voice traffic (for example, phone calls and faxes) over an IP network. Support for Cisco’s voice is deployed using the technology of voice packets. In VoIP, the digital signal processor (DSP) segments the voice signal into frames and stores them in voice packets. These voice packets are transported over the IP network, in accordance with specific protocols such as H.323 ITU-T (International Telecommunications Union-Telecommunications), also used for transmission of video over the IP network. As this is a delay-sensitive application, it is necessary to use equipment that supports Quality of Service parameters (QoS), and a well-defined network design.

What type of equipment do I need?

In order to use VoIP services, you will require a computer system along with the Internet access and a microphone, if your computer is not equipped with it. Although most VoIP providers and IP telephony connections require high-speed Internet, some can be used on dialup connections as well.

How can I make or receive a phone call?

Basically, the same way you would a regular phone, except you use your PC or IP phone. When you use VoIP, or Voice of an IP phone software on your computer, a phone usually appears on your screen. These telephones are called as SoftPhone and IP phones are called IPPhones or HardPhones.

The phone works on the computer like any other phone where you can dial numbers, or click a name of a contact pre-programmed, and press the call button. You will then hear the phone ring for the person you called and can then talk to him/her when you answer the call. When you receive a call, the phone will ring on your computer and you can click to accept the call and talk, or let ring (based on the number of rings you set) and route the call to voicemail or a forwarding number.

What type presents a VoIP Phone?

Typically a VoIP phone is not only capable of audio, but also can be used to maintain contacts list, for caller ID and call forwarding. Some IP phones even have webcam capabilities. The most popular VoIP software limits PC to PC calls to its own subscribers in order not to compromise the sound quality.

Typically a VoIP phone is not only capable of audio, but also can be used to maintain contacts list, for caller ID and call forwarding. Some IP phones even have webcam capabilities. The most popular VoIP software limits PC to PC calls to its own subscribers in order not to compromise the sound quality.

Advantages of IP Telephony and VoIP Servers / Services

1. Calls from IP phone to IP phone are free. You can talk endlessly with someone with an IP phone without paying anything beyond your Internet connection.

2. IP telephony providers offer drastically reduced costs for telephone calls to IP phones.

3. The cost of IP phone calls to cell phones are below those of traditional carriers.

4. Save up to 80% on current phone bills.

What are the costs for VoIP’s?

There are several options for soft phones that allow free calls between computers. There is also the option of signing of additional services paid for calls to landlines and mobiles. You should be aware of the fees and compare them with those of other carriers. In the case of IP phones you have the cost of equipment, but fares are generally cheaper and better service.

Care to Acquire VoIP Services :

1. Hidden costs

2. Lines unsafe – in some cases the conversations may be heard by others. This happens due to shared servers or open platforms, thus making you vulnerable to viruses, worms, Trojan horses, and unscrupulous hackers, which ultimately can corrupt your computer and disable it.

3. The inability to be used with dial-up connections. Check with your provider to avoid headaches.

4. Public listing of your name and / or phone number in published catalogs on the World Wide Web.

5. Many VoIP services bring spyware, compromising their safety.

Social Bookmarking

Prior to installation, you need to make sure all packages up-to-date. Run yum-y update. In case, any Kernel files were updated, the server will require reboot of the server. Now, you will need to download pre-requisites or essentials of Asterisk :

gcc
kernel-devel
bison
openssl-devel
doxygen #

In case you have a Dual Core Processor Server, Kernel-smp-devel is required through

apt-get update
apt-get install gcc kernel-devel bison openssl-devel

Or through yum

yum -y update
yum install gcc kernel-devel bison openssl-devel

Donwnload the latest version through asterisk website to /usr/src

In case you are using PRI cards, you need to the following :

wget http://ftp.digium.com/pub/libpri/releases/libpri-<version>.tar.gz

Untar the files :

tar -zxf zaptel-<version>.tar.gz
tar -zxf asterisk-<version>.tar.gz
tar -zxf libpri-<version>.tar.gz

Installation of Zaptel :

cd /usr/src/zaptel

make clean
make
make install

Restart Zaptel Service

Installation of LIBRI :

In case you are using E1 Cards, install LIBRI :

cd /usr/src/libpri

make clean
make
make install

Asterisk Installation :

cd /usr/src/asterisk

make mpg123 #
make clean
make
make install

If kernel is used, edit spinlock.h or Zaptel will not compile :

vi /usr/src/kernels/2.6.9-34.EL-x86_64/include/linux/spinlock.h

In Text Editor : define DEFINE_RWLOCK(x) rw_lock_t x = RW_LOCK_UNLOCKED
and change to define DEFINE_RWLOCK(x) rwlock_t x = RW_LOCK_UNLOCKED

Social Bookmarking