1 VOIP: Voice over Internet Protocol Broadband Phone Services

Introduction Voice over Internet Protocol (VoIP) is a protocol optimized for the transmission of voice through the Internet or other packet switched networks.  VoIP is often used abstractly to refer to the actual transmission of voice  VoIP is also known as IP Telephony, Internet telephony, Broadband telephony, Broadband Phone and Voice over Broadband. VoIP is the ability to make telephone calls over IP-based data networks with a suitable quality of service and superior cost-efficiency. 2

Introduction VoIP converts analog voice signals into digital data packets and supports real-time, two-way transmission of conversations using Internet protocol. VoIP calls can be made on the Internet using a VoIP service provider and standard computer audio systems. Some service providers support VoIP through ordinary telephones that use special adapters to connect to a home computer network. 3

Broadband Phone Service Broadband phone service [3]  Enables voice telephone calls to work over your high-speed Internet connection.  A broadband phone (also known as a VoIP or Internet phone) utilizes the same IP network as your Internet service.  Hardware adapters connect a standard telephone to the high-speed Internet connection to create a broadband phone. 4

Broadband Phone Service Hardware and software broadband phones are available [3].  Hardware broadband phones use an adapter (either as an add-on to your traditional phone or built in to an all-in-one phone unit).  The hardware is then connected to either the router on your network (via Ethernet) or your PC (via USB).  Software broadband phones use a software program to make broadband calls. 5 tial/products/voip/how_it_works.html

Broadband Phone Service Plans Service providers offer many different broadband phone subscription plans [3].  As with a cell phone, some service plans for these telephones feature unlimited local calling or large numbers of free minutes.  The cost of broadband phone service is highly variable; international, long distance and other calling charges often still apply. 6

Broadband Phone Reliability Compared to an Internet-based broadband phone network, the standard home voice telephone network is extremely reliable [3].  Calls cannot be made with the broadband phone whenever your home Internet service is down.  Additional failures within the broadband phone service itself will add to any downtime caused by the Internet connection. 7

Broadband Phone Sound Quality The sound quality supported by broadband phone service was significantly less than with traditional telephone services [3].  It can vary by provider and location, in general the quality of broadband phone audio is very good.  You might notice a small delay ("lag") between when you speak and the other party hears your voice. 8

Why choose VoIP [2] 9

Why choose VoIP [2] 10

Why choose VoIP [2] 11

Why choose VoIP [2] 12

Why choose VoIP [2] 13

Why choose VoIP [1] Cost reduction.  There can be a real savings in long distance telephone costs which is extremely important to most companies, particularly those with international markets. Consolidation.  The ability to eliminate points of failure, consolidate accounting systems and combine operations is obviously more efficient. Simplification.  An integrated voice/data network allows more standardization and reduces total equipment needs. Bandwidth efficiency:  PSTN networks reserve one pipe for every call. But in IP networks many calls can use the same pipe simultaneously. 14

Why choose VoIP [1] Important problems of fixed line telephony:  Limited extension of PBX  Imperfect simultaneous calls number  No common local (short) numbers between branches  Slow installation of changes in all telephony system – maintenance is done of few companies (cabling, PBX changes, system changes);  Limited ability to transfer, forward calls;  Paid calls between branches;  Slow and expensive installation when moving to new office;  No possibility to integrate telephony system with computer systems. Advantages of fixed line telephony  Well tried quality of calls, services  Well known technology 15

Why choose VoIP [1] Advantages of VoIP  Extra functions (conversations recording, statistics of calls.  Faster and cheaper installation of the system  Portability  Integration with computer systems  Free calls between company’s branches  Free calls in your network  Lower subscription fees  You can use your current LAN – no need to change infrastructure;  No limit to simultaneous calls  Not limited number of users connected to PBX  Remote and fast maintenance 16

References [1] [2] Peter Ingram, “Voice over Internet Protocol (VoIP) - An Introduction”, Ofcom, 18th January [3] 17

18 Computer Networks and Applications E-Commerce: Recommender Systems

19 Computer Networks [6] Types of Networks  Each computer or user in a network is referred to as a node.  The interconnection between the nodes is referred to as the communication link.  In most networks, each node is a personal computer, but in some cases a peripheral device such as a printer can be a node.

20 Computer Networks [6] The number of links L required between N PCs (nodes) is determined by using the formula L = N(N−1) / 2

21 Network Fundamentals [6] A network of four PCs.

22 Network Fundamentals [6] A star LAN configuration with a server as the controlling computer.

23 Network Fundamentals [6] A ring LAN configuration.

24 Network Fundamentals [6] A bus LAN configuration.

25 Internet Applications [6] The Internet is a worldwide interconnection of computers by means of a complex network of many networks. Anyone can connect to the Internet for the purpose of communicating and sharing information with almost any other computer on the Internet. The Internet is a communication system that accomplishes one of three broad uses:  Share resources  Share files or data  Communication.

26 Internet Applications [6] The primary applications of the Internet are:   File transfer  The World Wide Web  E-commerce  Searches  Voice over Internet Protocol  Video

27 Internet Applications [6] is the exchange of notes, letters, memos, and other personal communication by way of software and service companies. File transfer refers to the ability to transfer files of data or software from one computer to another. The World Wide Web is a specialized part of the Internet where companies, organizations, the government, or individuals can post information for others to access and use.

28 Internet Applications [6] E-commerce refers to doing business over the Internet and other computer networks, usually buying and selling goods and services by way of the Web. An Internet search allows a person to look for information on any given topic. Several companies offer the use of free search “engines,” which are specialized software that can look for websites related to the desired search topic.

29 Internet Applications [6] Voice over Internet Protocol (VoIP) is the technique of replacing standard telephone service with a digital voice version with calls taking place over the Internet. Video over Internet Protocol.  Video or TV over the Internet (IPTV) is becoming more common. The video (and accompanying audio) is digitized, compressed, and sent via the Internet. It is expected to gradually replace some video transmitted over the air and by cable television systems.

30 World Wide Web A system of globally unique identifiers for resources on the Web  Uniform Resource Locator (URL): Uniform Resource Locator Domain name is example.org. Resource identified as /wiki/Main_Page The publishing language HyperText Markup Language (HTML);HyperText Markup Language The Hypertext Transfer Protocol (HTTP).Hypertext Transfer Protocol

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32 World Wide Web

33 e-Commerce How to enhance e-Commerce sales?  Browsers into buyers  Cross-sell Recommender Systems!!

34 What are recommender systems? Recommender systems are systems which provide recommendations to a user  Too much information (information overload)  Users have too many choices Recommend different products for users, suited to their tastes.  Assist users in finding information  Reduce search and navigation time

35 Case Study: Amazon

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39 Personalized Product Recommendation?

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43 Which Sources of Information? Sources of information for recommendations: [1] Browsing and searching data Purchase data Feedback provided by the users Textual comments Expert recommendations Rating

44 Type of Recommendations [2] Population-based  The most popular news articles, or searches, or downloads  Frequently add content  No user tracking needed.

45 Type of Recommendations [2] Item-to-item  Content-based  One item is recommended based on the user’s indication that they like another item. If you like Lord of the Rings, you’ll like Legend.

46 Type of Recommendations [2] Challenges with item-to-item:  Getting users to tell you what they like Financial and time reasons  Getting enough data to make “novel” predictions. What users really want are recommendations for things they’re not aware of.

47 Type of Recommendations [2] Item-to-item  Most effective when you have metadata that lets you automatically relate items.  Genre, actors, director, etc. Also best when decoupled from payment  Users should have an incentive to rate items truthfully.

48 Type of Recommendations [2] User-based  “Users who bought X like Y.”  Each user is represented by a vector indicating his ratings for each product.  Users with a small distance between each other are similar.  Find a similar user and recommend things they like that you haven’t rated.

49 Type of Recommendations [2] User-based  Advantages: Users don’t need to rate much. No info about products needed. Easy to implement  Disadvantages Pushes users “toward the middle” – products with more ratings carry more weight. How to deal with new products? Many products and few users -> lots of things don’t get recommended.

50 How RS Work? Similarity Measurement [4]  For two data objects, X = (x1, x2,..., xn) and Y =(y1, y2,..., yn), the popular Minkowski distance is defined as  where n is the dimension number of the object and xi, yi are the values of the ith dimension of object X and Y respectively, and q is a positive integer. When q = 1, d is Manhattan distance; when q = 2, d is Euclidian distance

51 How RS Work? Similarity w u, v between two users u and v, or w i, j between two items i and j, is measured by computing the Pearson correlation [4] where the i ∈ I summations are over the items that both the users u and v have rated and is the average rating of the co-rated items of the u-th user

52 Example

53 Prediction and Recommendation Computation To make a prediction for the active user, a, on a certain item, i, we can take a weighted average of all the ratings on that item according to the following formula [4]

54 Example

55 Example

56 Example

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90 References [1] Aalap Kohojkar, Yang Liu, Zhan Shi, “Recommender Systems”, March 31, [2] Maria Fasli, “Agent Technology for e-Commerce”, Commerce.htmhttp://cswww.essex.ac.uk/staff/mfasli/ATe- Commerce.htm [3] Amit Tiroshi, Tsvi Kuflik, Judy Kay and Bob Kummerfeld, “Recommender Systems and the Social Web”, International Workshop at UMAP2011 on Augmenting User Models with Real World Experiences to Enhance Personalization and Adaptation, July 15, [4] Xiaoyuan Su, Taghi M. Khoshgoftaar, “A Survey of Collaborative Filtering Techniques”, Advances in Artificial Intelligence, Vol. 2009, [5] Badrul M. Sarwar, George Karypis, Joseph Konstan, and John Riedl, “Recommender Systems for Large- scale E-Commerce: Scalable Neighborhood Formation Using Clustering”, The Fifth International Conference on Computer and Information Technology (ICCIT 2002), [6] Louis E. Frenzel, Jr., “Principles of Electronic Communication Systems”, The third edition, McGraw-Hill, 2008.