Voice Over Internet Protocol. A VoIP Overview

Transcription

1 Voice Over Internet Protocol A VoIP Overview

2 What is VoIP Voice Over Internet Protocol is the assembling of voice into IP data. This data can then be transmitted over an IP network to an addressable ( IP address) destination Voice calls look like data calls VoIP calls are packet switched and analog calls are circuit switched Packet switched is data that is can be routed through different routes on a network to reach a destination Circuit switched is a connection where a physical path is dedicated between two end points

3 Why VoIP A major implementor of VoIP is to bypass long distance calls by transporting calls over an IP network VoIP allows communications on existing IP networks without adding additional lines or bandwidth Wireless adjuncts such as POS scanners and wireless handsets can roam and still be connected to the main office via IP

4 How does it work? Analog voice is received by a CODEC (coder / de-coder) Complex circuitry then samples the voice and compares the voice to a codebook. This codebook is used by both the coders and decoders. Once sampled and matched with the codebook the voice is now presented as data Some codebooks are of different sizes and have a different fidelity These codebooks are recommended standards that copies voice samples into different sizes Codec standards: G.711 changes voice into data but uses the same amount of space as an analog method. Uses 64K G.729 Uses a large codebook but sounds good at 1/8 of G.711. Uses about 8K G.729A Codebook smaller than G.729 G.729B Almost the same as G.729A but has silence suppression (most English conversations are silent 50% of the time and silence does not need to be transmitted) G.723 Very small codebook. Provides poor quality and uses K

5 Voice to IP Data Once voice is sampled and replaced by code the voice can then be formed into data and transported. The usual transport method uses the IP (Internet Protocol) standard. IP uses many layers associated with the OSI model to form, control, administer, and transport data. Most VoIP calls use a recommended standard that covers voice, video and data over IP networks. This standard is called H.323 H.323 encompasses many sub-standards that control setup, signaling, transport and terminations H.323 has migrated to several version with additional features and addendum's added to each version. H.323 is a developing standard which is continually being enhanced Other standards such as SIP and MGCP are also being developed but are not widely deployed

6 Voice to IP Analog Voice CODEC Compress Create Packet Add Headers Digital Network

7 IP to Voice Digital Network Process Header Decompress CODEC Analog Voice

8 Leading Technology? Not really. H.323 standard recommendations were developed for IP network video transport in 1996 In 1998 significant revisions were made to standardize the use of voice codec s This standardization prompted growth in the VoIP developers arena and the hope for a new revolutionary product VoIP has been around for many years in proprietary formats with gateways and piggy backing on existing data networks. An example of legacy VoIP products are the MICOM Communications Corporation s Network Integration products.

9 VoIP Quality? VoIP Quality of Service (QoS) factors involve latency (delay), packet loss and jitter (deviation or displacement of data) VoIP can provide a better quality of service (QoS) over a private Intranet or a managed LAN Multiple router hops, marginal bandwidth and security firewalls can destroy the QoS of a VoIP call To maintain high QoS, VoIP LAN management requires a Gatekeeper Gatekeepers give voice packets a priority over data packets. This is needed because voice packets are not re-tried in the event of an error on a VoIP call Gatekeepers perform admissions control (security), bandwidth control and call control signaling

10 VoIP and the Internet VoIP can be done over the Internet Quality will suffer depending on ISP and call packet routing VoIP call packets routed through different routers cause the routers to learn about the route the VoIP packet must take This learning causes the routers to re-send the setup message every time a different router is selected and causes latency Latency is increased by each device that traffic must pass through. If devices such as routers are very busy the latency through them can adversely affect voice quality Internet VoIP call packets may be routed through different routers during the call

11 Internet Topology Access Router ISP Edge Router POP/ NAP Edge Router POP/ NAP Access Router ISP Customer Router Customer Router VoIP Gateway Access Routers Core Routers/ SONET Access Routers VoIP Gateway Telephone

12 VoIP and the Intranet An unmanaged LAN (no gatekeeper) can provide an acceptable QoS Available bandwidth and data traffic must be considered Reduced cost of long distance has eliminated private voice networks Many companies still have private data networks VoIP calls would pass through known routers VoIP allows connectivity to main and branch office applications over existing data networks

13 Intranet Topology Firewall Internet ISP VoIP Gateway LAN Router Intranet Router LAN VoIP Gateway PC PC PC PC

14 VoIP Today VoIP has been a non-starter in the enterprise (private systems) market due to the plunge in toll costs A large number of voice calls today pass over VoIP connections End users are unaware of this underlying transport that they are using The absence QoS controls and standards deter adoption Inconsistent and sometimes unreliable service limits VoIP to private networks

15 What's Next for VoIP? More calls can be transported using VoIP making it a natural transport for long haul services Traditional voice calls use 64 kilobits VoIP calls using G.729 use 8 kilobits As the technology become more prevalent the cost will decrease and VoIP will prevail because of economic advantages More efficient networking with voice and data When the H.323 standard becomes more stable, Web, e- mail, fax or phone calls can be bundled together with seamless CTI integration.

16 What s Our Position? Samsung Telecommunications America believes in adopting new and emerging technologies STA has implemented VoIP standards into our products STA s approach is to provide a bridged solution The bridged solution will provide the quality, investment retention and features of our existing products but will allow the ability to add-on VoIP without wholesale system replacement