Cisco VoiP (Voice over IP)

CCMX Notes

• Note: Voice monitoring and recording are supported only on IPCC Express Enhanced and Premium Edition, not on Standard Edition.

• The VoIP silent monitoring server must be on the same VLAN as the agent phones and requires an available SPAN port.

Next

• Cisco BW calculations, and optimization. http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080094ae2.shtml#configvoice

  • Packet size, VAD

• VoiP Bandwidth savings.

  1. Codec: G.711 (64 Kbps) , G.729 (8 Kbps - Voice)(24 Kbps - with serial overhead) (32kbps - on ethernet)

  2. Changing Voice Payload Sizes
     • G.729 call with voice payload size of 20 bytes (20 ms):= 24 Kbps 40 bytes (40 ms):= 16 Kbps
       • Note: L2 headers are not considered in this calculation.
  3. RTP Header-Compression or Compressed RTP (cRTP)
     • Compressed Real-Time Protocol (cRTP) reduces the IP/UDP/RTP headers to 2or 4bytes (cRTP is not available over Ethernet).

• Call Admission Control

  • Locations, for systems with centralized call processing. Bandwidth (kbps)
  • Regions define the type of compression (G.711, G.723, or G.729) that is used on the link, and locations define the amount of available bandwidth for the link.
  • You assign each device in the system to both a region (by means of a device pool) and a location.
• Setup BRI at remote site for breakout using central callmanager, H.323

  •       !
          voice-card 0
            dspfarm
            dsp services dspfarm
          !
          voice call carrier capacity active
          voice rtp send-recv
          !
          voice service voip 
            h323
          !
          interface FastEthernet0/0.x
            description VOICE-Vlan
            ip address XX
            h323-gateway voip interface
            h323-gateway voip bind srcaddr XX
          !
          interface BRI1/0
            description ISDN-VoicePort
            no ip address
            isdn switch-type basic-net3
            isdn point-to-point-setup
            isdn incoming-voice voice
            isdn send-alerting
            isdn sending-complete
          !
          voice-port 1/0
            compand-type a-law
          !
          voice-port 1/1
            compand-type a-law
          !
          !
          dial-peer voice 20 voip
            destination-pattern 01132699..
            voice-class codec 1
            session target ipv4:10.110.0.102
            incoming called-number 01132699..
            dtmf-relay h245-alphanumeric
            no vad
          !
          dial-peer voice 3 pots
            destination-pattern .T
            progress_ind alert enable 8
            incoming called-number 9...
            direct-inward-dial
            port 0/1
            forward-digits all
         !

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CategoryCisco