NATIONAL INSTITUTE OF SCIENCE & TECHNOLOGY VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY [1] VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY ROLL # EC UNDER THE GUIDANCE OF N. SRINIVASU SUBMITTED BY

NATIONAL INSTITUTE OF SCIENCE & TECHNOLOGY VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY [2] INTRODUCTION What is VOIP ? Voice over Internet Protocol transfers voice through IP packets through the Internet. VoIP can use special hardware or a PC environment to achieve this purpose. How does VOIP works: Voice (source) - - ADC Internet DAC - - Voice (dest)

NATIONAL INSTITUTE OF SCIENCE & TECHNOLOGY VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY [3] PACKET FREQUENCY ●Packet frequency as the number of packets containing voice samples which are sent per second Components of H.323 ● Terminals ● Gateways ● Gatekeepers

NATIONAL INSTITUTE OF SCIENCE & TECHNOLOGY VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY [4] H.323 TERMINAL SUPPORTING OTHER PROTOCOLS ●H.245 : allowing the usage of the channels. ●Q.931: call signaling and setting up the call ●RTP: carries voice packets ●RAS: interacting with the gatekeeper

NATIONAL INSTITUTE OF SCIENCE & TECHNOLOGY VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY [5] GATEWAYS ●Interface between the PSTN and the Internet ●Translator : H.225 to H.221 or audio to video

NATIONAL INSTITUTE OF SCIENCE & TECHNOLOGY VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY [6] GATEKEEPERS ●Controls the end points under its zone Function ●Address Translation ●Admissions Control ●Call signaling ●Call Authorization ●Bandwidth Management

NATIONAL INSTITUTE OF SCIENCE & TECHNOLOGY VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY [7] H.323 PROTOCOL STACK

NATIONAL INSTITUTE OF SCIENCE & TECHNOLOGY VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY [8] DEFINITIONS Zone The collection of a gatekeeper and the endpoints registered with it is called a zone Network Address For each H.323 entity, a network address is assigned and this address uniquely identifies the H.323 entity on the network TSAP Identifier These TSAP identifiers allow multiplexing of several channels sharing the same network address

NATIONAL INSTITUTE OF SCIENCE & TECHNOLOGY VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY [9] CALL SETUP IN H.323 Endpoint enters the call setup phase Discovering a gatekeeper which would take the management of that endpoint The capability exchange takes place between the endpoint and the gatekeeper Registration of the endpoint with its gatekeeper The call is established

NATIONAL INSTITUTE OF SCIENCE & TECHNOLOGY VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY [10] MULTIPOINT CONTROL UNITS (MCU)

NATIONAL INSTITUTE OF SCIENCE & TECHNOLOGY VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY [11] SESSION INITIATION PROTOCOL (SIP) ●It is an application layer control protocol for creating, modifying and terminating sessions with one or more participants

NATIONAL INSTITUTE OF SCIENCE & TECHNOLOGY VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY [12] SIP MESSAGES  INVITE: for inviting a user to a call  BYE: for terminating a connection between the two end points  ACK: invitation for reliable exchange of messages  OPTIONS: for getting information about the capabilities of a call  REGISTER: gives information about the location of a user to the SIP registration server.  CANCEL: for terminating the search for a user

NATIONAL INSTITUTE OF SCIENCE & TECHNOLOGY VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY [13] SAMPLE SIP OPERATION

NATIONAL INSTITUTE OF SCIENCE & TECHNOLOGY VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY [14] SUPPORTING PROTOCOLS

NATIONAL INSTITUTE OF SCIENCE & TECHNOLOGY VOICE OVER INTERNET PROTOCOL SHREETAM MOHANTY [15] CONCLUSION ●Like everything else, as the technology changes so At first, only a few companies like Cisco and Lucent offered VoIP services, but the large telecommunications carriers – such as AT&T and Sprint -- are catching on ●VoIP is predominately used for personal instead of enterprise-wide use, but will the people who use it.