Do you know What is VoIP (voice over IP)

Do you know What is VoIP (voice over IP)


VoIP
Source - Wikipedia

Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Internet telephonybroadband telephony, and broadband phone service specifically refer to the provisioning of communications services (voice, faxSMS, voice-messaging) over the public Internet, rather than via the public switched telephone network (PSTN), also known as plain old telephone service (POTS).

 SOURCE - Wikipedia

Really there is not a way to say that cellphones have become a staple in the U.S. - Just like hamburgers or apple pie. A Mobile Phone is no longer a status symbol. It's as common as having a traditional landline telephone, and in some circles it's even more common. But as cellphone use accelerates, it's clear that data and voice plans may be in for a dramatic shift. That is, unless something changes in terms of wireless voice communications methods and payment options



If we put our ears on analysts , they just might hear such a shift occurring in the direction of Voice over Internet Protocol (VoIP) over 4G. Let's take a look.

Do some background reading on 4G in The Real Score on 4G Wireless.

How Does 3G Affect VoIP?

VoIP has been nothing short of revolutionary in the field of voice communications, as private branch exchanges (PBX) are increasingly pushed aside in favor of smaller, highly functional, IP-based call managers. Following closely behind all of this mass migration to VoIP is the reality that VoIP remains largely an Ethernet or landline-based technology. Rescuing VoIP from its landlocked exclusivity has been no small source of blood, sweat and tears on the part of voice communications researchers. And the effort to incorporate VoIP functionality into mobile devices has, until recently, faced sizable problems.

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the most foreboding problem is rooted in the current 3G infrastructure which - in Verizon networks - requires the almost exclusive use of the code division multiple access (CDMA) channel access method. Simply put, CDMA allows multiple users to transmit bits on a given medium, and each receiver differentiates between these transmissions by virtue of a code assigned to each bit. Due to the physics involved with CDMA, voice and data are typically transmitted via separate but parallel networks - circuit switched for voice, and packet switched for data, and herein lies the problem. Facilitating a VoIP call via 3G technology is not impossible in and of itself, as 3G is capable of transmitting data via packet switched networks, but according to Voxilla, 3G networks are still too unreliable and too scarce to prevent large numbers of dropped VoIP calls. Furthermore, until recently, the technology that would allow an end user to move from one area to another while in the midst of a VoIP call simply did not exist.

The rapid proliferation of 4G networks has led to an equally rapid advancement toward a VoIP solution that can maintain backward compatibility with legacy systems. According to Engadget, chip manufacturer Qualcomm successfully performed a voice call handoff from a 4G network to a 3G network in February 2012. This means that while conducting a voice call, Qualcomm officials were able to maintain connectivity when moving from an IP-based 4G network to a circuit-switched 3G network. This development was no small breakthrough, and could signal a solution to backward compatibility problems.


The most prevalent standard in 4G communications is 3GPP Long Term Evolution (commonly referred to as LTE). What makes LTE networks somewhat unique within the cellular industry is that they are exclusively packet switched. So, unlike the CDMA networks mentioned above, there is no separate but parallel network used for voice and data. Within LTE, everything is routed through an IP-based core, thereby eliminating the need for a separate voice network. The advantages to an exclusively IP-based network include higher throughput and less inter-cell multiuser interference. In the end, the proverbial voice and data plans offered by virtually all cell phone providers might become a thing of the past.

What the Future Holds
In 2009, after much outcry from its iPhone users, AT&T began allowing the use of VoIP services in its 3G network. AT&T had previously disallowed this for unclear reasons. Some suggested that AT&T did not want to lose revenue as it pertains to the various voice plans offered to its customers. Others suggested that AT&T did not want VoIP services to overshadow its core competency as a telephony company. Whatever the reasoning, the distinction between voice and data services is quickly going by the wayside. (Read about how VoIP can affect network security in VoIP - Backdoor to Your Network?)

Voice Over Internet Protocol (VoIP)

i. Network
ii. Backdoor
iii. Long Term Evolution (LTE)
iv. Fourth Generation Wireless (4G)
v. Third Generation Wireless (3G)
vi. 3rd Generation Partnership Project (3GPP)
vii. Distributed Computing System
viii. Hacking Tool
ix. Geotagging

What does Network mean?

What is network
Computer Network

A network, in computing, is a group of two or more devices that can communicate. In practice, a network is comprised of a number of different computer systems connected by physical and/or wireless connections.
The scale can range from a single PC sharing out basic peripherals to massive data centers located around the World, to the Internet itself. Regardless of scope, all networks allow computers and/or individuals to share information and resources.
Computer networks serve a number of purposes, some of which include:
i. Communications such as email, instant messaging, chat rooms, etc.
ii. Shared hardware such as printers and input devices.
iii. Shared data and information through the use of shared storage devices.
iv. Shared software, which is achieved by running applications on remote computers.

Early computer networks of the late 1950s included the U.S. military’s Semi-Automatic Ground Environment (SAGE) and the commercial airline reservation system called the Semi-Automatic Business Research Environment (SABRE).

Based on designs developed in the 1960s, the Advanced Research Projects Agency Network (ARPANET) was created in 1969 by the U.S. Department of Defense and was based on circuit switching – the idea that a single communication line, such as a two-party telephone connection, deserves a dedicated circuit for the duration of the communication. This simple network evolved into the present day Internet.
The basic hardware components that can be used in networks include:
  1. 1. Interface Cards: These allow computers to communicate over the network with a low-level addressing system using media access control (MAC) addresses to distinguish one computer from another.
  2. 2. Repeaters: These are electronic devices that amplify communication signals and also filter noise from interfering with the signals.
  3. 3. Hubs: These contain multiple ports, allowing a packet of information/data to be copied unmodified and sent to all computers on the network.
  4. 4. Bridges: These connect network segments, which allows information to flow only to specific destinations
  5. 5. Switches: These are devices that forward, make forwarding decisions and otherwise filter chunks of data communication between ports according to the MAC addresses in the packets of information.
  6. 6. Routers: These are devices that forward packets between networks by processing the information in the packet.
  7. 7. Firewalls: These reject network access requests from unsafe sources, but allow requests for safe ones.
  8. There are various types of networks, which are classified according to specific characteristics such as connection types, whether they are wired or wireless, the scale of the network, and its architecture and topology.

  9. Network types include local area networks, wide area networks, metropolitan area networks and backbone networks.
What does Backdoor mean?
backdoor

A backdoor is a technique in which a system security mechanism is bypassed undetectably to access a computer or its data. The backdoor access method is sometimes written by the programmer who develops a program.
A backdoor is also known as a trapdoor.
Backdoor threats increase when multiuser and networking operating systems are used by many organizations. In a login system, a backdoor used for system access may be in the form of a hard-coded username and password.
A network administrator (NA) may intentionally create or install a backdoor program for troubleshooting or other official use. Hackers use backdoors to install malicious software (malware) files or programs, modify code or detect files and gain system and/or data access. Even backdoors installed by network administrators pose security risks because they provide a mechanism by which the system can be exploited if discovered.


Long Term Evolution (LTE)

4G LETE
Long Term Evolution (LTE) refers to a standard for smooth and efficient transition toward more advanced leading-edge technologies to increase the capacity and speed of wireless data networks. LTE is often used to refer to wireless broadband or mobile network technologies.
LTE is also referred to as 3GPP Long Term Evolution. 3GPP is an acronym for 3rd Generation Partnership Project, which operates under a name trademarked by the European Telecommunications Standards Institute. LTE is also known as LTE Super 3G and LTE Super 4G.
LTE features include an all-IP flat network architecture, end-to-end quality of service (Qos), higher download rates approaching 300 mbps and upload rates of 75 mbps, expanding cell capacity to accommodate 200 active users and supporting fast moving mobiles.

LTE is referred to as the next generation network beyond 3G, with the capacity to support a high demand for connectivity from new consumer devices tailored to new mobile applications. In an LTE live air demo, Web browsing, HD video, and telecommunications are demonstrated simultaneously inside a single computer moving within a vehicle at 108 kilometers per hour.
In 2010, many well-known U.S. and global wireless service providers/manufacturers began using LTE.

Fourth Generation Wireless (4G)

What does Fourth Generation Wireless (4G) mean?
4G
Fourth generation wireless (4G) is an abbreviation for the fourth generation of cellular wireless standards and replaces the third generation of broadband mobile communications. The standards for 4G, set by the radio sector of the International Telecommunication Union (ITU-R), are denoted as International Mobile Telecommunications Advanced (IMT-Advanced).

An IMT-Advanced cellular system is expected to securely provide mobile service users with bandwidth higher than 100 Mbps, enough to support high quality streaming multimedia content. Existing 3G technologies, often branded as Pre-4G (such as mobile WiMAX and 3G LTE), fall short of this bandwidth requirement. The majority of implementations branded as 4G do not comply with the full IMT-Advanced standard.

The premise behind the 4G service offering is to deliver a comprehensive IP based solution where multimedia applications and services can be delivered to the user anytime and anywhere with a high data rate, premium quality of service and high security.

Seamless mobility and interoperability with existing wireless standards is crucial to the functionality of 4G communications. Implementations will involve new technologies such as femtocell and picocell, which will address the needs of mobile users wherever they are and will free up network resources for roaming users or those in more remote service areas.
Two competing standards were submitted in September 2009 as technology candidates for ITU-R consideration:

LTE Advanced - as standardized by the 3GPP


802.16m - as standardized by IEEE
These standards aim to be:
Spectrally efficient
Able to dynamically allocate network resources in a cell
Able to support smooth handover
Able to offer high quality of service (QoS)
Based on an all-IP packet-switched network
WiMax is touted as the first 4G offering. It is an IP based, wireless broadband access technology, also known as IEEE 802.16. WiMax services offer residential and business customers with basic Internet connectivity.

Present implementations of WiMAX and LTE are largely considered a stopgap solution offering a considerable boost, while WiMAX 2 (based on the 802.16m specification) and LTE Advanced are finalized. Both technologies aim to reach the objectives traced by the ITU, but are still far from being implemented.

Third Generation Wireless (3G)**

3G Related image3rd Generation Mobile Telecommunications (3G), is a set of standards that came about as a result of the International Telecommunication Union’s (ITU) initiative known as IMT-2000 (International Mobile Telecommunications-2000). 3G systems are expected to deliver quality multimedia to mobile devices by way of faster and easier wireless communications as well as “anytime, anywhere” services.

This term is also known as 3rd generation mobile telecommunications.
Techopedia explains Third Generation Wireless (3G)
There are two specifications-setting groups that cater to the objectives to 3G worldwide: 3GPP and 3GPP2.

3GPP 3G specifications are focused on evolved GSM (Global System for Mobile communication) core networks, known as UMTS (Universal Mobile Telecommunications Systems), and the radio access technologies based on them. This therefore includes UTRA (Universal Terrestrial Radio Access), GPRS (General Packet Radio Service), and EDGE (Enhanced Data rates for GSM Evolution).

3GPP2 3G specifications, on the other hand, are designed for CDMA2000 systems, which are based on CDMA (Code Division Multiple Access). Of the two, 3GPP specifications are more widely used owing to the fact that majority of the cellular networks on the planet are based on GSM.

Improved data rates of 3G systems over their predecessors have opened the doors for applications like mobile TV, video-on-demand, video conferencing, tele-medicine, and location-based services. High data rates have also allowed users to browse the Web using their cell phones and consequently gave birth to the term mobile broadband.

Subsequently, 3G paved the way for the rise of smartphones and their wide screens as they were more suitable for viewing mobile Websites, video conferencing, or watching mobile TV. It is no coincidence that the introduction of the iPhone in 2007 came at a time when 3G was gaining wide acceptance.

It took time for 3G to gain worldwide adoption. One major reason was that some 3G networks are not using the same frequency as the older 2G. This meant that wireless operators had to secure new frequencies and install new cell sites. Although first offered in 2001, global adoption of 3G only started to really gain traction sometime in 2007.

Distributed Computing System

Distributed computing system

Distributed computing is a computing concept that, in its most general sense, refers to multiple computer systems working on a single problem. In distributed computing, a single problem is divided into many parts, and each part is solved by different computers. As long as the computers are networked, they can communicate with each other to solve the problem. If done properly, the computers perform like a single entity.

The ultimate goal of distributed computing is to maximize performance by connecting users and IT resources in a cost-effective, transparent and reliable manner. It also ensures fault tolerance and enables resource accessibility in the event that one of the components fails.



The idea of distributing resources within a computer network is not new. This first started with the use of data entry terminals on mainframe computers, then moved into minicomputers and is now possible in personal computers and client-server architecture with more tiers.

A distributed computing architecture consists of a number of client machines with very lightweight software agents installed with one or more dedicated distributed computing management servers. The agents running on the client machines usually detect when the machine is idle and send a notification to the management server that the machine is not in use and available for a processing job. The agents then requests an application package. When the client machine receives this application package from the management server to process, it runs the application software when it has free CPU cycles and sends the result back to the management server. When the user returns and requires the resources again, the management server returns the resources was using to perform different tasks in the user's absence.

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