8.2.2 GatekeeperThe following are the general functions of a gatekeeper:• Dialled number-to-IP address translation• Authentication• Bandwidth controlThe gatekeeper provides these network management functions to registered clients. To register with thegatekeeper, you need to configure the V-IPGW16 card to use the gatekeeper and programme the GK Settingstable through system programming. For details, refer to "9.11 PBX Configuration—[1-1]Configuration—Slot—V-IPGW—Shelf Property— Gatekeeper Available" and "9.11.1 PBXConfiguration—[1-1] Configuration—Slot—V-IPGW—Shelf Property—GK Settings" in the PC ProgrammingManual. After programming, the V-IPGW16 card attempts to register with the gatekeeper using registrationinformation such as the IP address of the mother board, and destination telephone numbers specified in theGK Settings table.Note• For more information about gatekeeper functions, consult the documentation of the gatekeeper.• When using a gatekeeper, make sure to choose a compatible model. For more information aboutgatekeeper compatibility with the V-IPGW16 card, consult a certified dealer.8.2.3 Bandwidth AssessmentWhen using the IP telephones and V-IPGW16 card, you must ensure that the IP network in use has enoughbandwidth to support VoIP communications. If the amount of bandwidth required for VoIP communications ismore than the network can accommodate, speech quality will be compromised. In addition, there may be anadverse effect on the performance of other applications (e.g., e-mail or Web applications) that use the samenetwork. Therefore, care must be taken when assessing bandwidth requirements.Inform your network administrator of the required bandwidth, and make sure that the network can support VoIPcommunications even under conditions of maximum network traffic.Bandwidth Assessment for IP Extension CardRequired Bandwidth per IP Telephone for a CallThe required bandwidth depends on what combination of codecs and packet sending intervals is used. Keepin mind the following points about the type of codecs and packet sending intervals, in terms of speech quality:• The speech quality of the codecs varies as follows: (High) G.722, G.711, G.729A (Low)*1• The shorter the packet sending interval, the higher the speech quality.• The higher the speech quality the IP telephones provide, the more bandwidth the IP telephones require.*1 When the preferred codec of each party differs, the call will be established using the lower codec. For example, if the caller prefersG.711 while the called party prefers G.729A, the call will be established using G.729A.CodecPacket Sending Interval20 ms 30 ms 40 ms 60 msG.722*1/G.711 87.2 kbps 79.5 kbps — —G.729A 31.2 kbps 23.5 kbps 19.6 kbps 15.7 kbps*1 G.722 is only available for calls between KX-NT300 series IP-PTs, KX-NT500 series IP-PTs, and some SIP phones that support thiscodec during peer-to-peer communication. For details, refer to "5.2.3 Peer-to-Peer (P2P) Connection" in the Feature Guide.280 Installation Manual8.2.3 Bandwidth Assessment
