Elastic SIP Trunking | Twilio

Trunks. Twilio Elastic SIP Trunking is a cloud based solution that provides connectivity for IP-based communications infrastructure to connect to the PSTN, for ... TwilioDocs SMS Voice Runtime Video Studio Alldocs... English English 日本語 Deutsch Français Português SDKs Help Login Signup SMS Voice Runtime Video Studio Alldocs... SDKs Help Login Signup ElasticSIPTrunking Twilio Menu ElasticSIPTrunking Configure ElasticSIPTrunking Scale&limits IPaddresses Codecs CallsperSecond(CPS)—TrunkingTermination EmergencyCallingforSIPTrunking ExtendedCallDuration SIPHeaderManipulation ConfigureyourTrunkusingTwilioInterconnect TestyourElasticSIPTrunk ProtectyouraccountwithVoiceDialingGeographicPermissions Troubleshooting TestyourElasticSIPTrunk TroubleshootingyourTrunk VoiceInsights SolutionBlueprintsandConfigurationGuides SolutionBlueprints ConfigurationGuides APIReference ElasticSIPTrunkingRESTAPIReference CredentialListResource IPAccessControlListResource OriginationUrlResource PhoneNumberResource TrunkResource EmergencyCallingforSIPTrunkingAPI ProgrammableVoiceAPIOverview Pricing:TrunkingResource Libraries C#/.NET Java Node PHP Python Ruby Collapse Expand Ratethispage: GettingStarted:ConfigureyourTwilioElasticSIPTrunk BeforeYouBegin InordertouseTwilioElasticSIPTrunking,you'llneedaTwilioaccount.Signupfor afreeTwilioaccountifyoudon'talreadyhaveone. ConfigureyourElasticSIPTrunk: ConfigureTrunks Generalsettings Terminationsettings Originationsettings Numbers ConnectyourNetworkover PublicInternet TwilioInterconnect Twilio'sIPaddresses Features Codecs CallsperSecond CallRecording SecureTrunking CallRedirect ExtendedCallDuration SIPDiversionHeaders CallTransferviaSIPREFER DisasterRecoveryURL EmergencyCalling CallerName:CNAMLookup&CNAMRegistration TrustedCallingwithSTIR/SHAKEN SIPHeaderManipulation ConnectwithyourIPcommunicationsinfrastructure: ElasticSIPTrunking-SolutionBlueprints ElasticSIPTrunking-ConfigurationGuides RESTAPIdocumentation: ElasticSIPTrunkingRESTAPIReference Requirements InordertouseTwilioElasticSIPTrunking,you'llneedtoensurethatyou havethefollowing: ASIPenablednetworkelement(e.g.SessionBorder Controller,SIPCallServer,IP-PBX,SIP-PRIIAD,etc.)withaccesstotheinternet. SufficientInternetbandwidthtosupportthepeakcalltraffic.Thepeak bandwidthcanbedeterminedby: SIPTrunkPeakBandwidth=MaxSimultaneousCallsx100kbps The100kbpsvaluereflectsthenecessarybandwidthfortheG711codecplussufficientroomforoverhead. Dashboard Logintotheconsoleandgotothe"ElasticSIPTrunking"section.Your Dashboardwillbedisplayed,providingahighleveloverviewofyour Trunkingusage:Minutes,Calls&Cost. Ontheleftnavigationmenuyou'llhavelinksto: Overview:Getstartedhere,reviewtutorialdocs,oraccessfeatures&pricing. Manage:AccessTrunks,IPaccesscontrollists,credentiallists,ornetworkinginfo. Manage Underthe"Manage"menuyouwillhaveaccesstoalloftheconfiguration aspectsofyourTrunks.Specifically,youwillhavelinksto: Trunks:ListofyourexistingSIPTrunks.Create,deleteand configureyourtrunks. IPAccessControlLists:ManageyourIPAccessControlLists(asetofIPs thatareallowedtoreachyourSIPDomain). CredentialLists:Manageyourusercredentials(asetofusernamesand passwordsthatareallowedtoreachyourSIPDomain). NetworkingInfo:ImportantinformationaboutTwilio'splatformthatyouwill needtoconfigureyourcommunicationsinfrastructure. Trunks TwilioElasticSIPTrunkingisacloudbasedsolutionthatprovides connectivityforIP-basedcommunicationsinfrastructuretoconnecttothePSTN, formakingandreceivingtelephonecallstothe'restoftheworld'viaany broadbandinternetconnection. Atrunkiscomposedofthefollowingsettings: General:Provideafriendlynameforyourtrunkandseeitsuniqueidentifier (TrunkSID). Termination:Configurethesettingsforplacingoutgoingtrafficfromyour communicationsinfrastructuretothePSTN. Origination:Configurethesettingsforreceivingincoming trafficonyourTwilionumberstodelivercallstoyour communicationsinfrastructurefromthePSTN. Numbers:Allowsyoutoassociatenumberswithagiventrunk,andseeall numberscurrentlyassociatedwithatrunk. FromtheTrunksnavigationbaritemyou'llbeabletoviewafull listofyourElasticSIPTrunksandclickoneachonetomodifyits configuration.Youalsohavetheabilitytodeleteagiventrunkfromthis view. CreateaTrunk FromtheTrunksnavigationbarclickon"CreateNewTrunk"to createanewtrunk.ThismayalsobedonefromtheGetting Startedsection. Generalsettings Thesesettingsapplytotheentiretrunkregardlessofthedirectionofyour traffic. FriendlyName Provideafriendlynameforyourtrunk. TrunkSID Thisistheuniqueidentifierofthistrunk,andisassignedautomaticallyonce youcreateatrunk. CallRecording Fromthisdrop-downyoucanenablecallrecordingforthistrunk.Whenenabled, allcallsarerecorded(bothoriginationandterminationtraffic),ina pay-as-you-goconsumptionmodel.Recordingoptionsforasinglechannelordualchannels canbeselected.ThedefaultsettingofatrunkisDoNotRecord.Youcanselect: DoNotRecord:Recordingisdisabledonthistrunk. Recordfromringing:Recordingwillbeginwhentheringingstarts. Recordfromanswer:Recordingwillbeginwhenacallisanswered. DualRecordfromringing:Recordingwillbeginwhentheringingstartsandbothtrackswillbevisualizedseparately. DualRecordfromanswer:Recordingwillbeginwhenacallisansweredandbothtrackswillbevisualizedseparately. RecordingTrim:Ifenabled,silencewillbetrimmedfromtherecording.Ifdisabled,silencewillnotbetrimmedfromtherecording. ExtendedCallDuration TwilioextendedthemaximumcalldurationonElasticSIPTrunkingcallsfrom4hoursto24hours.Thisallowsthebusinesstohaveextendedconversationsthatlastlongerthan4hours.Youcanseedetailshere. SecureTrunking Encryptionensuresthatthecallmediaandassociatedsignallingremainsprivateduringtransmission.TransportLayerSecurity(TLS)providesencryptionforSIPsignalingandSecureReal-timeTransportProtocol(SRTP)providesencryptionforcallcontent/mediapackets.LearnabouthowtoenableandtroubleshootTLSissuesfromthisblog. TheTLSprotocolisdesignedtoestablishasecureconnectionbetweenaclientandaservercommunicatingoveraninsecurechannel.RFC5246,theTransportLayerSecurity(TLS)Protocol,Version1.2,specifiesVersion1.2oftheTransportLayerSecurity(TLS)protocol. TLSSpecifications: SupportedTLSversions:TLSv1.0,TLSv1.1andTLSv1.2. PLEASENOTE:Tobettercomplywithsecurityrequirements,wehavedeprecatedTLSv1.0andTLSv1.1forinboundandoutboundElasticSIPtrunkingcalls. IfyourSIPinfrastructurerequiresusingTLSv1.0orTLSv1.1,youcanconfigureyourTwilioAccounttoallowthesedeprecatedversionsinyourconsoleunderVoice→Settings→AllowDeprecatedSIP/TLSversions.Ifthissettingisenabled,yourSIPendpointscanusethedeprecatedTLSv1.0andTLSv1.1versionsforSIPsignalingsenttoorreceivedfromTwilio.Ifdisabled,onlynon-deprecatedTLSv1.2+isallowed. TwiliostronglyrecommendstheuseofTLSversion1.2whenconnectingyourSIPinfrastructure. SupportedCiphers:ECDHE-ECDSA-AES128-GCM-SHA256,ECDHE-RSA-AES128-GCM-SHA256,ECDHE-ECDSA-AES128-SHA256,ECDHE-RSA-AES128-SHA256,ECDHE-ECDSA-AES256-GCM-SHA384,ECDHE-RSA-AES256-GCM-SHA384,ECDHE-ECDSA-AES256-SHA384,ECDHE-RSA-AES256-SHA384,AES128-GCM-SHA256,AES128-SHA256,AES128-SHA,AES256-GCM-SHA384,AES256-SHA256,AES256-SHA SRTPprovidesaframeworkfortheencryptionofRTP&RTCP.RFC4568,SessionDescriptionProtocol(SDP)SecurityDescription(SDES)forMediaStreams,definessuchaprotocolspecificallydesignedtoexchangecryptographicmaterialusinganewlydefinedSDPcryptoattribute. SRTPSpecifications: TrunkingOrigination:Onlyasinglecryptosuitewillbeincluded:AES_CM_128_HMAC_SHA1_80 TrunkingTermination:CryptosuitessupportedincludeAES_CM_128_HMAC_SHA1_80andAES_CM_128_HMAC_SHA1_32.Bothmaybeincludedinanorderofpreference. Theoptionalmasterkeyidentifier(MKI)parameterisnotsupported WhenSecureTrunkingisenabled,anynon-encryptedcallswillberejected.PleaseensureyouconfiguretheuseofTLSinyour OriginationSettingsbyincludingthetransport=tlsparameter.IfthetransportparameterispresentonanyofyourURIsspecifyingadifferenttransport(e.g.transport=udp),itwillbeignoredandTLSwillbeused.Bydefaultport5061willbeusedforTLS,howeveryoumayspecifytheportyouwishtouseinyourOriginationURI. ImportingTwilio'sRootCACertificate TLSisusedtoencryptSIPsignalingbetweenSIPendpoints.InorderforthistofunctionproperlyitisrequiredthatcertaindevicesinthenetworkimportanSSLcertificate.TwiliousescertificatesfromaCA(CertificateAuthority).Itisimportantthatyouaddthefollowingrootcertificatetoyourcommunicationsinfrastructuretoestablishitsauthenticityonthenetwork.DownloadTwilio'sCAcertificate. ItisimportanttonotethatTwiliousesawildcardcertificatewhichcanbeusedformultiplesubdomainsofadomain(*.pstn.twilio.com).Ifyournetworkelementdoesnotsupportwildcardedcertificatespleasedisablecertificatevalidation. TLS/SRTPsupportwithAsterisk Asteriskshipsbydefaultwithchan_sipdriverandworkswellwithTwilio.However,ifyouhavesomereasontorunPJSIPdriverwithAsterisk,pleasenotethefollowing: Asterisk13.8cert2defaultstoPJSIP2.5anditdoesnotworkwithTwilioforTLS/SRTPpurposes.Non-encryptedcallsdowork Asterisk13.8cert2canalsousethelatestPJSIPdriver,whichatthistimeis2.5.5.Twilioworkswellwithitdespitethefollowingmessageappearinginyourlog: PJSIP2.5.5outputsthefollowingerrorbutthecallisstillshowntowork. Sep2713:03:56]ERROR[10886]:pjproject:0>:tlsc0x7f217c03RFC5922(section7.2)doesnotallowTLSwildcardcertificates.AdviseyourSIPprovider,please! Thefollowinglinkisaguidetoinstallinganon-bundledversionofPJSIP.Changetheversionto2.5.5inthesteps. InstallingPJSIPchanneldriver CallTransferviaSIPREFER WhenCallTransferisenabled,TwiliowillconsumeanincomingSIPREFERfromyourcommunicationsinfrastructureandcreateanINVITEmessagetotheaddressintheRefer-Toheader.Pleasegohereformoredetails. MediaSettings SymmetricRTP Ingeneral,yourIPcommunicationsinfrastructureshoulduseyourpublicIPaddressintheSDPandthatwillbetheONLYdestinationwhereTwiliowillsendmediatowards.However,ifyou’retraversinganon-SIPawareNAT,youmaynotknowyourpublicIPandyourSDPwillincludeyourprivateIPaddress,typicallyleadingtoone-wayaudioissues.TwilioisabletoresolvethisbylatchingontotheincomingRTPmediastreamandsendingRTPtowardsthatdestinationbyenablingSymmetricRTP. WhenSymmetricRTPisenabledTwiliowilldetectwheretheremoteRTPstreamiscomingfromandstartsendingRTPtothatdestinationinsteadoftheonenegotiatedintheSDP.PleasenotethatthissettingismorevulnerabletoRTPattacks. WhenSymmetricRTPisdisabled,TwiliowillsendRTPtothedestinationnegotiatedintheSDP.Thissettingisconsideredtobemoresecureandthereforerecommended. TerminationSettings Configuringyourterminationsettingswillallowyoutoplaceoutgoingtraffic fromyourcommunicationsinfrastructuretothePSTN.Inordertouseatrunk forterminationitmusthaveaTerminationSIPURIandatleastone authenticationscheme(IPAccessControlListsand/orCredentialsLists). TerminationURI ConfigureaSIPDomainNametouniquelyidentifyyourTerminationSIPURIfor thistrunk.ThisURIwillbeusedbyyourcommunicationsinfrastructureto directSIPtraffictowardsTwilio. {example}.pstn.twilio.com Twiliorecommendsthatyouuseadashinsteadofadottoimprovereadabilityofyourdomain. However,insomecasesyoumaypreferasub-domainlikea.b.pstn.twilio.comofthehigher-leveldomainb.pstn.twilio.com Asub-domainlikea.b.pstn.twilio.comcanbecreatedunderthefollowingrequirements: Thehigher-leveldomain(b.pstn.twilio.com)mustbecreatedfirst Thehigher-leveldomain(b.pstn.twilio.com)mustbecreatedbythesameaccountortheparentaccount Configureatrunkonyourcommunicationsinfrastructure(e.g.IP-PBXorSBC) Configureatrunkonyourcommunicationsinfrastructureandpointittowards {example}.pstn.twilio.comforoutboundtraffictowardsTwilio. LocalizedTerminationURIs Ifyouwishtomanuallyconnecttoaspecificgeographicedgelocationthatisclosestto thelocationofyourcommunicationsinfrastructure,youmaydosobypointing yourcommunicationsinfrastructuretoanyofthefollowinglocalized TerminationSIPURIs: {example}.pstn.ashburn.twilio.com(NorthAmericaVirginia) {example}.pstn.umatilla.twilio.com(NorthAmericaOregon) {example}.pstn.dublin.twilio.com(EuropeIreland) {example}.pstn.frankfurt.twilio.com(EuropeFrankfurt) {example}.pstn.singapore.twilio.com(AsiaPacificSingapore) {example}.pstn.tokyo.twilio.com(AsiaPacificTokyo) {example}.pstn.sao-paulo.twilio.com(SouthAmericaSãoPaulo) {example}.pstn.sydney.twilio.com(AsiaPacificSydney) YoucanfindthelegacylocalizedURIslisthere.eg:{example}.pstn.us1.twilio.com RedundancywithTerminationURIs Twilio'sElasticSIPTrunkingusesanFQDN({example}.pstn.twilio.com)asaTerminationURIthatisusedbyyourcommunicationsinfrastructuretodirectSIPtraffictowardsTwilio.Asexplainedintheprevioussection,localizedTerminationURIsareavailable. Forexample,{example}.pstn.ashburn.twilio.com,thisspecificFQDNresolvesinthefollowingDNSA-Record: Type IPAddress TTL A 54.172.60.3 10min A 54.172.60.0 10min A 54.172.60.2 10min A 54.172.60.1 10min Foreachedgelocationwehave3-4IPaddressesthatareusedforreliabilitypurposes(seeIPaddresses.EachoftheseIPaddressesrepresentsauniquepublicedgeforourElasticSIPTrunkingservicesintotheTwiliocloud,distributedacrossmultipleAvailabilityZonesforreliabilitypurposes. ItishighlyrecommendedthatyoudonotpegtowardsasingleIPaddressbutratherutilizeallIPaddressesandfailoverincaseoneIPisnotresponding. Acommonstrategy,whichwedeployinternallyandwhatwehaveinstructedourcarrierstodotowardsusaswell,isthatifthereisnoresponsetoanINVITE,gotothenextIPafter4seconds.AsinglemachinebehindasingleIPwillalwaysfailatsomepointsotheoverallsolutionmusttakethatintoconsiderationandguarditselftowardsthesefailures. Furthermore,ifthereisacompleteAshburnoutage,itisrecommendedthatyoufailovertoanotheredgelocation(e.g.Ifconnectingtoashburn,failovertoumatilla),keepinginmindthattheEdgeLocationwillinturnresolveto3-4differentIPaddressesforreliability. Authentication Configuretheauthenticationdetailstoensurethesecurity/authenticityofyourterminationtraffic.YoumustconfigureaminimumofeitheranACLorcredentialauthentication.Ifyouconfigureboth,thenbothACLsandcredentialsareenforced. ItishighlyrecommendedthatyouconfigureUserCredentials.IPACL'salonedoesnotprotectagainstcertaintypesofattacks. TocreateanewAccessControlList(ACL): Click"CreateIPAccessControlList"fromthe"Authentication"section. GivetheAccessControlListafriendlynamethatisdescriptiveofwhatthat listofIPs.Somethinglike"DallasDatacenterIPs". AddIPstoyournewIPAccessControlList(theseshouldbetheIPaddresses usedforoutboundSIPtrafficbyyourCommunicationsInfrastructureborder elements,e.g.SBC). GiveyourIPsafriendlynamethatisdescriptiveofwhatthatIPis,for example"ProductionSBC". Click"CreateACL" TocreateanewCredentialList: Click"CreateCredentialList"fromthe"Authentication"section. GivetheCredentialListafriendlynamethatisdescriptiveoftheuser you'reauthenticating.Somethinglike"Admin,Twilio". Enterausername(theseshouldbetheusernameusedfordigestauthentication foroutboundSIPtrafficbyyourcommunicationsinfrastructureborder elements,e.g.SBC). Enterthecorrespondingpasswordforthatuser. Click"CreateCredentialsList" IfyouareusingUserCredentials,yourSIPINVITEwillbechallengedwitha 407ProxyAuthenticationRequiredrequestingtheappropriateusercredentials. Bytheendofthisstepyourtrunkwillbeabletoprocessterminationcalls fromyourcommunicationsinfrastructure,viaTwilio,tothePSTN. AllowedCallerIDNumbersinTerminationcalls YoumustspecifyaCallerIDNumberthateithercorrespondstoaTwilioDIDonyouraccountoraCallerIDNumberthathasbeenverifiedontheConsoleorwiththeOutgoingCallerIDAPI. IfaCallerIDNumberisnotspecifiedintheSIPINVITE'sFromField,thentheRemote-Party-IDortheP-Asserted-Identitywillbeused. ForTrialaccounts,inadditiontousingaverifiedCallerID,youcanonlycallnumbersthatarealsoverified.Toremovethisrestriction,UpgradeyouraccountviatheConsole. MakeyourfirstTerminationcall INVITEsip:+15108675309@{example}.pstn.ashburn.twilio.comSIP/2.0 MakesurethatanyphonenumberssentviaSIPtoTwilioarealwaysE.164-formatted(e.g.+12128675309).IfE.164formatisnotused,thenthecallwillberejectedwithaSIP400BadRequestresponse. MakesureyourE.164formattednumberalwaysincludes+.Thisplusprefixisamust. Originationsettings Configuringyouroriginationsettingswillallowyoutoreceiveincoming trafficfromthePSTNtoaTwilionumber,deliveredtoyourcommunications infrastructure.Withphonenumbersavailableinover100countries,Twiliogives youatrulyglobalSIPTrunk.AminimumofoneTwilionumbershouldbe associatedwiththistrunkifyou'reconfiguringitfororigination. Theoriginationsettingsconfiguredinthissectionwillapplytoallnumbers associatedwiththistrunk. OriginationSIPURI ConfigureyouroriginationSIPURI,whichidentifiesthenetworkelemententry pointintoyourcommunicationsinfrastructure(e.g.IP-PBX,SBC).ThehostpartoftheSIPURImaybe eitheranIPaddressoraFullyQualifiedDomainName(FQDN). sip:172.56.42.132 sip:mysbc.com TwiliowillautomaticallypopulatetheuserpartoftheSIPURIbasedonthe TwilionumberthecallfromthePSTNisdestinedtowards.Forexample,ifthe callfromthePSTNisreceivedforTwilionumber+14158675309,whichis associatedwiththistrunk,theresultingURIsenttoyourcommunications infrastructurewillbe: sip:[email protected] sip:[email protected] Alternatively,youmayalsoconfigureaspecificuser-part(e.g."anniebp") withintheoriginationSIPURI.NotethatthesameURIwillbeusedforall Numbersassociatedwiththistrunk.Hence,ifthecallfromthePSTNis receivedforTwilionumber+14158675309,whichisassociatedwiththistrunk, theresultingURItowardsyourcommunicationsinfrastructurewillstillbethe followingforallphonenumbers: sip:[email protected] sip:[email protected] Note:TheTwilionumberdialed(+14158675309)willalwaysbeconveyedin aSIPDiversionheaderforTrunkingOriginationcalls. X-headers ItispossibletosendanySIPheaderbeginningwiththeX-prefix,by appendingthemtotheoriginationSIPURI.Forexample,youcouldconfigure: sip:[email protected]?X-myheader=foo tosendX-myheader:fooonalloriginatedcalls. Thetransportparameter Bydefault,TwiliosendsoriginatingSIPrequeststowardsyourcommunicationsinfrastructureoverUDP.ThismaybecustomizedtobesentoverTCPratherthanUDP.ChangethisbyusingthetransportparameterintheoriginationSIPURI: sip:[email protected];transport=tcp Alternatively,youmaycustomizeittouseTLSforSIPsignalling.WhenusingTLS,thedefaultportwillbe5061,howeveradifferentonemaybespecified.ChangethisbyusingthetransportparameterintheoriginationSIPURI,andoptionallybyspecifyingadifferentportnumber: sip:[email protected]:5062;transport=tls Note:ElasticSIPTrunkingOriginationURIconfigurationsusingthesipsURIschemeinordertoenableend-to-endencryptionisNOTsupportedbyTwilio.However,wedosupportsipURIschemesusingtransport=tlsforpoint-to-pointencryption. IfyouconfigureyourElasticSIPTrunkingOriginationURIstousesipsschemes,thesesipsURIswillbehandledasiftheyweresipURIsusingTLStransport.TwiliowilleffectivelyadjusttheURIinternallytoinsteadberoutedusingthesipschemeandtransport=tlsontheoutboundmessages,resultinginpoint-to-pointencryptionbetweenTwilioandthecustomerequipment. TwiliostronglysuggestsnotusingsipsschemesinyourTwilioSIPconfigurations,asthiscouldcausepossiblyunintendedbehavior,duetohowweprocesssuchURIs.Instead,wesuggestusingsipschemeswithTLStransport.Thismethod,alongwiththesecurityofourvoicearchitectureandSuperNetwork,isaneffectivewayofaddingencryptiontoyourTwilioSIPconnections. Theedgeparameter TospecifythegeographicedgefromwhichTwiliowillsendtheoriginatingSIPtraffictowardsyourcommunicationinfrastructure,youmustincludetheedgeparameterinyourOriginationSIPURI.Forexample,iftheedge=dublinparameterisincludedinyourOriginationSIPURI,TwiliowillsendtheSIPtrafficfromtheEuropeIrelandedgelocation: sip:[email protected];edge=dublin Iftheedgeparameterisnotspecified,TwiliowillsendtheOriginatingSIPtrafficfromtheedgelocationwheretheincomingPSTNcallcomesin. Note:YoumustmakesureyouallowtheIPaddressesoftheTwilioedgelocationforSIPsignallingandRTPmediatraffic. Thisparameterwaspreviouslynamedregionanditisstillsupported.Viewalistoflegacyregionidentifiershere.eg:sip:[email protected];region=ie1 UsingMultipleOriginationSIPURIs Itispossibletoconfigureuptoten(10)OriginationSIPURIswithdifferentpriority&weight. ThepriorityfielddeterminestheprecedenceofuseoftheSIPURI.TwiliowillalwaysusetheSIPURIwiththelowest-numberedpriorityvaluefirst,andfallbacktootherSIPURIsofequalorhighervalueifthesessiontothatSIPURIfails. IfaservicehasmultipleoriginationSIPURIswiththesamepriorityvalue,TwiliowillusetheweightfieldtodeterminewhichSIPURItouse.TheweightvalueisrelevantonlyinrelationtootherSIPURIswiththesamepriorityvalue. PriorityrankstheimportanceoftheURI.Valuesrangefrom0to65535,wherethelowestnumberrepresentsthehighestimportance.WeightisusedtodeterminetheshareofloadwhenmorethanoneURIhasthesamepriority.Itsvaluesrangefrom1to65535.Thehigherthevalue,themoreloadaURIisgiven. ItispossibletoenableordisableanoriginationSIPURI.WhenanoriginationSIPURIisenabled,it'sactiveintherouteselection.Ifitisnotenabled,thenitwillnotbeusedforroutingtraffictowardsyourcommunicationsinfrastructure. Inthefollowingexample,boththepriorityandweightfieldsareusedtoprovideacombinationofloadbalancingandfailoverservices. OriginationSIPURI Priority Weight sip:mysbc1.com 10 60 sip:mysbc2.com 10 20 sip:mysbc3.com 10 20 sip:mysbc-backup.com 20 10 ThefirstthreeSIPURIsshareapriorityof10,sotheweightfield'svaluewillbeusedTwiliotodeterminewhichservertocontact.Thesumofallthreevaluesis100,sosip:mysbc1.comwillbeused60%ofthetime.ThetwoSIPURIssip:mysbc2.comandsip:mysbc3.comwillbeusedfor20%ofrequestseach.Ifsip:mysbc1.comisunavailable,thesetworemainingmachineswillsharetheloadequally,sincetheywilleachbeselected50%ofthetime. Ifallthreeserverswithpriority10areunavailable,therecordwiththenextlowestpriorityvaluewillbechosen,whichissip:mysbc-backup.com. Note:IfanyofthefollowingSIPstatuscodesarereturned("2xx","400","404","405","410","416","482","484","486","6xx"),TwiliowillnotfailovertothenextoriginationSIPURI.IfthereisnoSIPresponsefromagivenserver,Twiliowillfailoverafter4seconds. DisasterRecoveryURL Inthecaseofadisasterpreventingyourcallsfrombeingdeliveredtoyour originationSIPURIabove,youcanconfigureaDisasterRecoveryURLpointing toanapplicationbuiltonTwilio'spowerfulscriptingtoolcalledTwiML.You canuseTwiMLtobuildanapplicationthatwillmanagecallsasrequiredby yourdisasterrecoveryplan,includingreplicatingthefunctionalityofyour PBX(e.g.IVR). http://fallback.mycompany.com/index FormoreinformationonbuildingyourTwiMLapplication,pleaserefertothe TwilioQuickStartandTwiMLAPIGuide.Pleasenotethatwhencallsare redirectedtoyourdisasterrecoveryURL,normalTwilioVoiceratesapply:seevoice pricing. CNAMLookups CNAMisanacronymwhichstandsforCallerIDName.CNAMisusedtodisplaythecallingparty'snamealongsidethephonenumber,tohelpuserseasilyidentifyacaller. WhenyouenableCNAMLookup,theCallerIDNameisinsertedintheSIPINVITEviathe“From”,and“Contact”and(ifapplicable)“P-Asserted-Identity”fieldsforeachcaller. NotethatCNAMlookupsforUS/CAnumbersarebilledperlookup,evenifdatamaynotbeavailable.Currently,requestingCallerIDNameLookupforinternationalnumberswillreturnnullvalues,butwillnotbebilled. EnablethisFeatureUsingtheTwilioConsole: ToenableCNAMLookupusingtheconsole,logintotheconsoleandgotothe"ElasticSIPTrunking"section. WhenyouhaveselectedaTrunk,navigatetothe“Origination”Settings(viatheleft-handsub-menu).Here,youwillseeaswitchwhereyoucanenableCNAMLookup.Youwillknowthesettinghasbeenenabledwhentheswitchhasturned‘blue’andtheword‘ENABLED’appears. CNAMLookupmustbeenabledonaperTrunkbasis CNAMLookupisonlysupportedforUS/CAphonenumbers CNAMLookupisbilledpersuccessfullookup(thisincludesthecasewheretheNameisnotavailableforaNumberintheCNAMNationaldatabases).ItisknownthatmanyAT&TnumbersarenotpublishedtotheCNAMNationaldatabases. CNAMLookupisbilledpersuccessfullookup,evenifthecallitselffails CallRedirect CallredirectenablesyoutoredirectaTrunkingOriginationcall.YourcommunicationsinfrastructurecanredirectanincomingINVITEbyrespondingwithaSIP302(MovedTemporarily).Thisresponsecontainsacontactheaderfieldwiththenewaddressesthatshouldbetried. Twiliosupportsasingleredirectionpercall: IfaredirectedtargetalsosendsaSIP302responsetoanothertarget,Twiliowillfailthecall. TwiliohonorsthefirstURIoftheSIP302response:MultipleURIsintheSIPContactheaderexceptthefirstoneormultipleSIPContactheadersexceptthefirstonewillbeignored. CallredirectionstowardsTwiliodomains(*.sip.twilio.comor*.pstn.twilio.com)arenotsupported IfthecallistoaregisteredSIPendpoint,redirectionisnotallowed TheedgeparameterisnotsupportedinaSIP302contactURI.Theredirectedcallwillusethesameegressedgelocationastheoriginalcall ThetnxparameterisnotsupportedinaSIP302contactURI.TheredirectedcallwillusethesameInterconnectConnectionastheoriginalcall IfSecureTrunkingwasusedfortheoriginalINVITEthentheredirectedcallwillalsouseTLS/SRTP IfCallRecordingwasusedfortheoriginalINVITEthentheredirectedcallwillalsoberecorded SIPDiversionHeaders TrunkingOrigination WhenTwilioreceivesincomingtrafficonyourTwilionumbersfromthePSTNtobedirectedtoyourcommunicationsinfrastructure,itwilladdaSIPDiversionheadernotingtheTwilionumberthatwasdialed.ThisheaderservesasahistoricalrecordthatindicatesthatthecallwasdivertedfromthedialednumbertotheOriginationSIPURIofyourSIPTrunk.AnexampleofwhatthisDiversionheadermightlooklikeisshownbelow. Diversion: TrunkingTermination WhenTwilioreceivesoutgoingtrafficfromyourcommunicationsinfrastructuretothePSTN,yourSIPmessagecansometimesincludeSIPDiversionheadersifthecallwaspreviouslyforwarded.TwiliowillforwardSIPDiversionheadersitreceivestothecarriers. TocombatanymaliciousadditionofDiversionheaders,TwiliowillcheckallDiversionheadersitreceivesthatcontaintheTwiliodomain.TwiliowillverifythatthephonenumberincludedintheheadermatchesoneassociatedwithyourTwilioaccount(eitheraTwilionumberownedbytheaccountoraverifiedCallerID).Iftheheaderfailsthischeck,Twiliowillremovetheheader. Numbers Fromthistabyouwillbeableto: BuyanewTwilioNumberforyourTrunk ViewallTwilioNumberscurrentlyassociatedwiththisTrunk AssociateanexistingTwilioNumberwiththisTrunk DisassociateaTwilioNumberfromthisTrunk ViewallTwilioNumberscurrentlyassociatedwiththisTrunk Inthe"Numbers"sectionyouwillbeabletoviewallnumberscurrentlyassociatedwiththistrunk.Recallthatallofthesenumberssharethesameorigination&generalsettings. Youmayclickonagivennumbertoview/modifyitsconfiguration. BuyanewTwilionumberforyourtrunk AminimumofasingleTwilioPhoneNumberisrequiredtobeabletoreceiveincomingcallsfromthePSTNtoyourcommunicationsinfrastructureviayourTwilioTrunk. Makesureyouhaveallyourtrunkconfigurationchangessaved,andthenfromthe"Numbers"sectionselect"BuyaNumber". Selectthecountrycode,andsearchforavailablenumbersmatchinganypatterns(e.g.+14158675309)youmightwanttolookforinyournumber. OnceyoufindtheTwilionumberyouwouldliketobuy,goaheadandpurchaseitandcontinuetosetupyournumber. Thiswilltakeyoutothenumberviewwhereyoucanmodifytheconfigurationforthatnumber. Underthe"Voice"sectionselectthe"SIPTrunking"radiobutton,andfromthedropdownlistbelowselectthedesiredSIPTrunkyouwouldliketoassociatethisNumberwith.Don'tforgettosaveyourconfigurationchanges. AssociateanexistingTwilionumberwiththistrunk Inthe"Numbers"sectionselect"AssociateaNumberwiththisTrunk",whichwilldisplayalistofallofyourexistingTwilionumbers.Clickontheoneyouwouldliketoassociatewiththistrunk. Thiswilltakeyoutothenumberviewwhereyoucanmodifythatnumber'sconfiguration.Underthe"Voice"section,selectthe"SIPTrunking"radiobutton,andfromthedropdownlistbelowselectthedesiredSIPTrunkyouwouldliketoassociatethisnumberwith.Don'tforgettosaveyourconfigurationchanges. DisassociateaTwilioNumberfromthisTrunk Youcandisassociateanumberfromatrunkinseveralways: Fromthe"Numbers"sectionofagiventrunk,youcandirectlydisassociateaphonenumberfromthenumberslistdisplayedbyclickingonthetrashbutton. Bychangingthe"Voice"configurationofagivennumbertoadifferenttrunkorbyconfiguringitwithanapplicationorURL Bydeletingthetrunkassociatedwiththatnumber Notethatwhenyoudothis,thenumberisdisassociatedfromthetrunkbutitisnotreleasedfromyouraccount. Twiliophonenumbersarebilledonamonthlybasis.Unlessyouareactivelyusinganumber,oryouwanttokeepanumberreservedforfutureuse,youcanreduceyourcostsbyreleasingyourunusednumbers.Inordertoreleasethenumber,gotothe"VoiceandMessaging"section,clickon"Numbers"andreleasethedesirednumberfromthatpage. Receiveyourfirstoriginationcall Makeyourfirsttestcallbydialingyourtrunk'sTwilionumber,e.g. +14158675309,andensureyourcorrespondingcommunicationsinfrastructure extensionrings. DeleteaTrunk Youcandeleteatrunk: Fromthe"Trunks"section,usingthetrunkslistdisplayed.Notethatwhen youdothis,allnumbersassociatedwiththistrunkwillbeautomatically disassociatedfromthetrunkbutnotreleased.Inordertoreleaseitplease gotothe"VoiceandMessaging"section,clickon"Numbers"andreleasethe desirednumbersfromthatsection. Fromanyofthetrunkspecificconfigurationscreensyouwillhavetheoption to"DeletethisTrunk". Notethatwhenyoudothis,allnumberspreviouslyassociatedwiththistrunk willbedisassociatedfromthetrunk,buttheywillnotbereleasedfromyour account.Twiliophonenumbersarebilledonamonthlybasis.Unlessyouare activelyusinganumber,oryouwanttokeepanumberreservedforfutureuse, youcanreduceyourcostsbyreleasingyourunusednumbers.Inordertorelease thenumber,pleasegotothe"VoiceandMessaging"section,clickon"Numbers" andreleasethedesirednumberfromthatsection. YourNetwork PrepareyourcommunicationsinfrastructuretomakesurethatyourSIP infrastructurehasconnectivitytoTwilioandviceversa. ConfigureyourTerminationURIsforyourTwilioTrunk,optionallyusinga LocalizedTerminationURIifyouwishtomanuallyconnecttoaspecific geographicedgelocationoftheTwilioplatform. AllowallofTwilio'ssignallingandmediaIPaddressesandportsonyour firewall. Configureyourinfrastructurenottoregisterforthistrunk. Ensureyourinfrastructurewillsendaminimumvalueof20forMax-Forwards toensureyourcallisprocessedsuccessfully. EnsurethatanyphonenumberssentviaSIPtoTwilioarealways E.164-formatted. Optionallyset-upyourCommunicationsInfrastructuretoissueSIPOPTIONSmessagesasapingmechanismtoyourElasticSIPTrunk(SendtheMessageRequestTo:TerminationURIyoucreated(example.pstn.twilio.com));theTwilioplatformwillrespondappropriately.PleasemaintainthePinglowerthan1SIPOPTIONSevery10-15secondstoavoidyourrequestsfrombeingbannedbyourPlatform. DeployingbehindaNAT Ifyou’redeployingbehindaNATwithoutaSessionBorderController,it’simportanttokeepopentheNATtranslationbinding. ForSignaling,whenusingUDP,thismaybeachievedbyperiodicallysendingSIPOPTIONStoTwilio,whichwillrespondwitha200OK. ForSignaling,whenusingTCPorTLS,thismaybeachievedbyperiodicallysendingSIPOPTIONStoTwilio,orCR-LFkeep-alives(periodicallysendingadouble-CRLF(the"ping")thenwaittoreceiveasingleCRLF(the"pong”)fromTwilio),thelatterhasthesmallestoverhead. ForRTP,thisisusuallylessofanissueasmediapacketsaresentmorefrequently. IPaddresses YouMUSTallowALLofTwilio'sfollowingIPaddressrangesandportsonyourfirewallforSIPsignallingandRTPmediatraffic.ThisisimportantifyouhaveNumbersindifferentedgelocationsandforresiliencypurposes(e.g.ifNorthAmericaVirginiagatewaysaredown,thenNorthAmericaOregongatewayswillbeused).Twiliodoesnotguaranteewhichedgelocationthemediawillegressfrom,withoutusingtheedgeparametersinceitcandependonwhichPSTN-SIPGatewaydeliversthecalltowhichTwilioedgelocation. PleaseseeTwilio'sElasticSIPTrunkingIPaddressesforthecompletelist. Forfurtherinformationtohelpyouconfigureyourinfrastructurewithyour TwilioElasticSIPTrunk,refertotheSIPTrunkingconfigurationguides. Ratethispage: YouareviewinganoutdatedversionofthisSDK. NextSample ExampleJSONresponse Thankyouforyourfeedback! Pleaseselectthereason(s)foryourfeedback.Theadditionalinformationyouprovidehelpsusimproveourdocumentation: IfapplicablefillinthecountrieswhereyouareusingTwilio Missinginformationorcode Contentisconfusingorhardtofollow Inaccurateoroutdatedinformation Brokenlinkortypo Didnotsolvemyproblem Contentiseasytofollow Solvedmyproblem Other Sendyoursuggestions Needhelp?TalktoSupport ProtectedbyreCAPTCHA–Privacy-Terms Sendingyourfeedback... 🎉Thankyouforyourfeedback! Somethingwentwrong.Pleasetryagain. Thanksforyourfeedback! Referusandget$10in3simplesteps! Step1 Getlink Getafreepersonalreferrallinkhere Step2 Give$10 Yourusersignsupandupgradeusinglink Step3 Get$10 1,250freeSMSesOR1,000freevoiceminsOR12,000chatsORmore Learnmoreaboutthereferralprogram