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					                                                                              VoIP
                                                      SSS
                                             1
                               1
                                                 ,
                                         2

                                    ,                ,
                         : 0-2544-1197, Email: nattaphat_p@yahoo.com
          2


                                                       10325
              : 0-2697-6701,         : 0-2275-4892, Email: wanchai_rat@utcc.ac.th


                                                                              VoIP

                                         VoIP

              VoIP
                                                               VoIP
                     2
                                                                             SSS
       VoIP
                                                          Delay
                                                     Call Center

                                                                   VoIP Gateway
                                                                     Call Center


                                                                      VoIP

: Voice over IP, VoIP,                                 ,
1.    น
      SSS      (                          )              . . 2539
248

                                     (Internet Service Provicer)
              VoIP                                                  PC-to-PC
PC-to-Phone                                                             VoIP

                                    VoIP           SSS
                                                                                     ๆ


      VoIP


                     VoIP
                                                                      VoIP
                         SSS
                                                                                 ๆ
                                                       VoIP PC-to-PC
                                                    VoIP
                               IP Phone                SSS                      IP Phone
                                                                               2

                                                                                10




(PING)                                         ๆ

                     ๆ
                                                                                  ๆ

         VoIP




                 แผนภ พ 1

2. แน แ
Voice over IP (VoIP)                               (Voice)
(Data Network)       Internet Protocol (IP)
                          Internet, Intranet                      ๆ           IP Protocol
                               VoIP
(Internet Telephony    IP Telephony)
                                                        (Long Distant Call)
                                            VoIP                              2
 2.1    ภพ                    (Voice Quality)


                       - Delay         ๆ

                       - Packet Loss

                       - Jitter                                 Delay
                                               Packet
                              - Transmission Rating Factor (R – Value)

                                                          ๆ
                                      (Mouth to Ear)

                                        R
                                      (ITU)= Ro – Is – Id – Ie-eff + A

     R = transmission Rating Factor
   Ro = the basic signal-to-noise ratio including noise sources
   Is = a combination of all impairments simultaneously with voice signal
   Id = a combination of all impairments caused by delay
   Ie-eff = impairments caused by low bit rate codecs and includes impairment     due to packet losses of random
distribution
   A = the advantage factor, which allows for compensation of Impairment      factors when there are other
advantages of access to the user


                              - Mean Opinion Score (MOS)

                                      (Subjective)

                                              ITU                                 MOS
                                  MOS = 1 + 0.035R + 7 x 10 - 6R(R - 60)(100 - R)
                                  Score     R-Value

 2.2        ภพ                        (Service Quality)




3.             น             แ               น
                                                                            (Voice
Quality)
1                                  (Voice Quality)




                           2
    -                              (End-to-End)       X1-X4


    -                                       (VoIP Section)
            X2-X3
        VoIP                                VoIP

        (VoIP Gateway)




    แผนภ พ 2                                VoIP
                               2
    - Toll Quality

    - Below Toll (PSTN)
                 Quality
                                                     Toll
        Quality
                                                                         (Service Quality)


         2                                                           (Service Quality)




* = Parameters considered by ETSI EG201 796

4. ผ                นผ        ภพ                            VoIP                      SSS
                                                                        VoIP
                                                         (Network Transmission Performance)
                                          Delay       Packet Loss

                              PING
(Packet)                                          (Codec)      ๆ

                                                                            Delay, Packet Loss,
Jitter                                                                       R-Value      MOS
Score                                              VoIP            SSS
   3
           SSS




แผนภ พ 3
                 SSS

                       VoIP   SSS
4
           SSS




แผนภ พ 4
                 SSS




ๆ
               - Quality Factor Class A :
                                                       30%
               - Quality Factor Class B :
                  30% - 70%
               - Quality Factor Class C :
                                                    70%

                     VoIP                      SSS
                                                          Delay Time
                                (Call Setup Time)
                       Call Center

                                                             ๆ

     ๆ                               VoIP Gateway
                                         Call Center
5.     ผ
                                            VoIP                       SSS


                                                     Delay
                                                     Call Center

Toll Quality          VoIP
                                             .

                                                 ๆ

       น
             .,             .
       น                        น      ภ          www.ntc.or.th,          , 15
              2551                               ( .),              น        Voice
over Internet Protocol, www.ntc.or.th,            ,            2549
AVAYA Inc., AVAYA IP Voice Quality Network Requirements, www.avaya.com, USA,
April 2006
CISCO Systems Inc., CISCO IP Solution Center Quality of Service User Guide 3.2,
www.cisco.com, USA, 2004
Communication Alliance Ltd., Quality of Service Parameters for Voice over Internet
Protocol Services, www.acif.org.au, Australia, October 2007
European Telecommunications Standards Institute (ETSI), ETSI EG 201 769 v1.1.2,
www.etsi.org, France, October 2000
International Telecommunication Union (ITU), ITU-T Recommendation E.430, G.107,
G.109, G.114, X.135, X.136, Y.1541, www.itu.org, Switzerland
Uganda Communication Commissions,Quality of Service Parameters, www.ucc.co.ug
Malaysian Communications and Multimedia Commission, Proposal for the
Determination of Mandatory Standards for Quality of Service,
www.mcmc.gov.my, Malaysia, 8 Apr 2002
Nepal Telecommunication Authority, Quality of Service Parameters for Basic
Telephone Service, www.nta.gov.np, 26 Jun 2007
Shailenda K. Hajela & Mohinder P. Singh, QoS Benchmarks for Voice over Internet
Protocol Services, 7th APT Standardizaion Program Forum, www.aptsec.org,
India, August 2003
Telecom Regulatory Authority of India, Regulation on Quality of Basic and Cellular
Mobile Telephone Services, www.trai.gov.in, India, 1 July 2005

				
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