Axio C8110 - Learn More; SIP Protocol and NAT Traversal

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AXISC8110NetworkAudioBridge

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SessionInitiationProtocol(SIP)

TheSessionInitiationProtocol(SIP)isusedtosetup,maintainandterminateVoIPcalls.Youcanmakecallsbetweentwoormore

parties,calledSIPuseragents.TomakeaSIPcallyoucanuse,forexample,SIPphones,softphonesorSIP-enabledAxisdevices.

TheactualaudioorvideoisexchangedbetweentheSIPuseragentswithatransportprotocol,forexampleRTP(Real-Time

TransportProtocol).

Youcanmakecallsonlocalnetworksusingapeer-to-peersetup,oracrossnetworksusingaPBX.

Peer-to-peerSIP(P2PSIP)

ThemostbasictypeofSIPcommunicationtakesplacedirectlybetweentwoormoreSIPuseragents.Thisiscalledpeer-to-peerSIP

(P2PSIP).Ifittakesplaceonalocalnetwork,allthat’sneededaretheSIPaddressesoftheuseragents.AtypicalSIPaddressinthis

casewouldbesip:<local-ip>

Example

SIP

sip:192.168.1.101 sip:192.168.1.100

YoucansetupaSIP-enabledphonetocallanaudiodeviceonthesamenetworkusingapeer-to-peerSIPsetup.

PrivateBranchExchange(PBX)

WhenyoumakeSIPcallsoutsideyourlocalIPnetwork,aPrivateBranchExchange(PBX)canactasacentralhub.Themain

componentofaPBXisaSIPserver,whichisalsoreferredtoasaSIPproxyoraregistrar.APBXworkslikeatraditionalswitchboard,

showingtheclient'scurrentstatusandallowingforexamplecalltransfers,voicemail,andredirections.

ThePBXSIPservercanbesetupasalocalentityoroffsite.Itcanbehostedonanintranetorbyathirdpartyprovider.Whenyou

makeSIPcallsbetweennetworks,callsareroutedthroughasetofPBXs,thatquerythelocationoftheSIPaddresstobereached.

EachSIPuseragentregisterswiththePBX,andcanthenreachtheothersbydialingthecorrectextension.AtypicalSIPaddressin

thiscasewouldbesip:<user>@<domain>orsip:<user>@<registrar-ip>.TheSIPaddressisindependentofitsIP

addressandthePBXmakesthedeviceaccessibleaslongasitisregisteredtothePBX.

Example