Transcript VoIP
Voice Over Internet Protocol “VoIP” Muayyed Al Kadhem Abdulkhaleq Al Musaleem Content Introduction VoIP Vs Traditional Phones Types of VoIP Advantages Disadvantages How VoIP Works Conclusion Introduction VoIP “Voice over Internet Protocol” Definition: The routing of conversation over IP-based network (Internet) Packet switching instead Circuit switching VoIP is any Protocol used to carry audio signals over an IP network Introduction The first VoIP protocol: 1973 for APRANET VoIP can not only be used over the Internet but also in a private network Types of VoIP There are three types of VoIP service: 1. Analog Telephone Adaptor (ATA): - the simplest and most common way. It is an analog-to-digital converter. It connects a phone to a computer or directly to internet connection. Service providers for this type is Vonage & AT&T. VoIP Vs Traditional Phones VoIP has better efficiency than traditional phones. In VoIP, there is no different between a local and international call. However, it depends on the service provider. Types of VoIP 2. IP Phones: - they look like normal phones but instead of having the standard RJ-11 (phone connectors), IP phones have an RJ-45 (Ethernet connector) Types of VoIP 3. Computer-to-Computer: - the easiest way to use VoIP. Advantages The big advantage is the cost • VoIP to VoIP • VoIP to PSTN Direct Inward Dialing “DID”: Connect the caller directly to the VoIP user. DID usually has a monthly fee. Access Numbers: Requires the caller to input the extension number of the VoIP user. This costs usually as a local call. Advantages Functionality • Incoming calls are routed anywhere you are connected to the Internet. • Include video conversation, messaging or data file exchanging. • Only Voice in one location in traditional Circuit switched telephony. Advantages Mobility • enables a user to access all of their telecommunication services, and to make and receive calls, on any terminal. • Software like Skype & Yahoo Messenger provide mobility all over the world if we have an Internet access. Disadvantes Reliability • IP does not provide a mechanism to ensure that data packets are in sequential order • There will be a momentary drop out of voice because some of packets are delivered out of order or even delayed and lost. • The receiving node must restructure the packets that received out of order. Disadvantages DSL: already uses a traditional phone line which reduces the benefits of VoIP Integration In a common global standard: • The traditional phone line & mobile phones share a common global standard (E.164), while VoIP doesn’t share. Disadvantages Demand on VoIP • because of mobile phones have already achieved complete market penetration, there is low demand on VoIP. Security • VoIP doesn’t support any type of encryption which makes it easy to listen in and change the content. Also, it is susceptible worms and virus although it is rare. How VoIP Works Circuit switching: • connection is open and constant bitrate, packet switching: • opens a brief connection, just long enough to send a small chunk of data “packets” from one system to another. How VoIP Works Step 1: • The caller’s voice is digitized as the existing phones. This can be done by the telephone company (which is how carriers use IP in their networks), by an Internet service provider (ISP), or by a PC on your desk. How VoIP Works Step 2: • Next using complex algorithms the digital voice is compressed and then separated into packets; and using the Internet protocol, the packets are addressed and sent across the network to be reassembled in the proper order at the destination. Again, this reassembly can be done by a carrier, and ISP, or by one’s PC. How VoIP Works Step 3: • During transmission, packets could be lost or delayed, or errors may damage the packets. • Conventional error correction techniques would request retransmission of unusable or lost packets, but if the transmission is a real-time voice communication that technique obviously would not work, so sophisticated error detection and correction systems are used to create sound to fill in the gaps. • This process stores a portion of the incoming speaker’s voice, and uses a complex algorithm to “guess” the contents of the missing packets and create new sound information to enhance the communication. How VoIP Works Step 4: • After the packets are transmitted and arrive at the destination, the transmission is assembled and decompressed to restore the data to an approximation of the original form. Conclusion The benefits of VoIP over traditional phone. VoIP still has challenges. Questions??