Voice over IP IS 311 IT IN BUSINESS Voice over Internet Protocol Robert Heger Michelle Le Dana Nartea Assaf Maoz November 19 2002 0 Voice over IP VOICE OVER INTERNET PROTOCOL Background U S government agencies realized the importance and the potential of internet technology several years ago The potential of internet technology was generously funded by the Advanced Research Projects Agency ARPA resulting in a global Internet Part of the ARPA technology was to create a set of network standards that specify the details of how computers communicate as well as a set of conventions for interconnecting networks and routing traffic Officially this standard is called TCP IP and is the standard by which computers communicate across any set of interconnected networks whether they are connected internally all within one network or connected through networks that span geographic distance Therefore TCP IP is the base technology for the global Internet that connects over 170 million individuals in homes schools corporations and government labs in virtually all populated countries The global Internet allows subscribers to share information with anyone around the world as easily as they share it in the next room An outstanding success the Internet demonstrates the viability of the TCP IP technology and shows how it can accommodate a wide variety of underlying network technologies Transmission control protocol and Internet protocol work differently making the feasibility of this standard to handle a wide variety of underlying networking needs possible TCP is a connection orientated circuit that gets established between two hosts and exchanges streams of data TCP is considered a reliable protocol because it guarantees both the delivery of the data and the order of the packets that it is sending However this connection requires constant bandwidth to maintain the connection Internet protocol is a connection less orientated circuit that works at the packet also known as datagram level and is considered to be an unreliable protocol IP specifies the format of packets and the addressing scheme Most networks combine IP with the higher level protocol TCP Internet protocol is considered unreliable because it allows IP packets datagrams to be sent in any order and be received in any order By utilizing this protocol several individual packets can be sent and switched in bulk to their forward location The true benefit of IP is that several types of information can be encapsulated with individual IP packets For the purpose of this paper we will look at the encapsulation of voice and their transmission using an IP packet Internet Model The most common standard now for open connectivity amongst networks is the 5 layer Internet model The Internet model provides a flow from the application level where it begins to the physical layer where information is sent in and out of the computer The Internet model has standardized the assent and decent of a datagram in transmission 1 Voice over IP The Internet s 5 Layer Model top down hierarchy Application used by application program the start of the five layer process Transport establishing end to end connections translates domain names into numeric addresses and segments messages also known as the TCP layer Network responsible for end to end addressing and routing determines destination address if unknown also known as IP layer Data Link deals with message delineation error control network access Physical defines how information will be transmitted through the network VoIP Concepts The Internet is once again changing the way people communicate through the use of Voice over Internet Protocol VoIP technology Every month millions of people worldwide are discovering and harnessing the power of the Internet According to Global Reach as of March 2002 there were over 561 million Internet users in the world making VoIP more commonplace Recently according to the International Engineering Consortium IEC the Internet is composed of more than 130 000 networks worldwide VoIP is the transmission of voice traffic in packets Black 1 In simple terms it is the transmission of voice using IP In some cases two computer users who are logged onto the Internet will run a program that has VoIP capability Depending on the VoIP application a user may be required to input an IP address of the computer to which he or she wishes to connect Other software may provide users with Buddy Lists which show their contacts and whether they are online or not Depending on the software if a remote user on the buddy list is online a user may simply select the user with whom he or she wishes to chat with and send them a request to chat with most applications When a buddy list is used the IP address does not need to be known by the user because the IP was determined by the application itself Some very common and popular software which either come standard with most Microsoft operating systems with Internet Explorer or are free to download and use are the following Microsoft NetMeeting MSN Messenger ICQ AOL Instant Messenger Yahoo Messenger 2 Voice over IP Vocaltec Inc was the first company to introduce VoIP in February of 1995 with their Internet Phone software This initial software was developed for 486 Mhz machines with a sound card speakers microphone and a modem The Internet Phone software simply compressed the voice signal into Internet Protocol IP packets and transmitted them across the Internet to another user This transmission was between a PC and a PC and would only function when both users were using the same software People often assume that in order to speak using VoIP that there still must be two computers using the same software as in the first case with Vocaltec s Internet Phone software however this is not true PC callers are not limited to only calling other PC users A PC caller can also reach telephone users by way of a Public Switched Telephone Network PSTN For this to work a gateway located as near to the call receiver as possible is used to convert the Internet call into a PSTN call The following are two commercial providers of these gateways AccessPower www accesspower com Delta Three http www deltathree com There are multiple aspects of VoIP and how it transmits voice packets These terms according to Black are as follows Internet telephony Placement of telephone calls over the public Internet internet telephony Placement of telephone calls over a private network IP telephony Use of IP to