Schema
SIP Fallback Handler Response
The response your fallback handler returns when Ultravox forwards an unmatched incoming SIP call to it.
The response a customer-hosted SIP fallback handler returns to Ultravox when Ultravox receives an incoming SIP INVITE that does not match any configured agent allowance. The handler decides how to dispatch the call by returning one of the variants below.
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Ultravox Data Message ProtocolProtocol documentation for messages exchanged between client and server during Ultravox calls.
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{
"startAgentCall": {
"templateContext": {},
"initialMessages": [
{
"text": "<string>",
"invocationId": "<string>",
"toolName": "<string>",
"errorDetails": "<string>",
"callStageMessageIndex": 123,
"callStageId": "<string>",
"callState": {},
"timespan": {
"start": "<string>",
"end": "<string>"
},
"wallClockTimespan": {
"start": "<string>",
"end": "<string>"
},
"metadata": {}
}
],
"metadata": {},
"medium": {
"webRtc": {
"dataMessages": {
"pong": true,
"state": true,
"transcript": true,
"clientToolInvocation": true,
"dataConnectionToolInvocation": true,
"playbackClearBuffer": true,
"callStarted": true,
"debug": true,
"callEvent": true,
"toolUsed": true,
"userStartedSpeaking": true,
"userStoppedSpeaking": true,
"invokingTool": true
}
},
"twilio": {
"outgoing": {
"to": "<string>",
"from": "<string>",
"additionalParams": {}
},
"dtmfHandling": {
"ignore": true,
"userTextMessage": {
"text": "<string>"
}
}
},
"serverWebSocket": {
"inputSampleRate": 123,
"outputSampleRate": 123,
"clientBufferSizeMs": 123,
"dataMessages": {
"pong": true,
"state": true,
"transcript": true,
"clientToolInvocation": true,
"dataConnectionToolInvocation": true,
"playbackClearBuffer": true,
"callStarted": true,
"debug": true,
"callEvent": true,
"toolUsed": true,
"userStartedSpeaking": true,
"userStoppedSpeaking": true,
"invokingTool": true
},
"mediaIdleTimeout": "<string>"
},
"telnyx": {
"outgoing": {
"to": "<string>",
"from": "<string>",
"additionalParams": {}
},
"dtmfHandling": {
"ignore": true,
"userTextMessage": {
"text": "<string>"
}
}
},
"plivo": {
"outgoing": {
"to": "<string>",
"from": "<string>",
"additionalParams": {}
},
"dtmfHandling": {
"ignore": true,
"userTextMessage": {
"text": "<string>"
}
}
},
"exotel": {
"dtmfHandling": {
"ignore": true,
"userTextMessage": {
"text": "<string>"
}
}
},
"sip": {
"incoming": {},
"outgoing": {
"to": "<string>",
"from": "<string>",
"username": "<string>",
"password": "<string>"
}
}
},
"joinTimeout": "<string>",
"maxDuration": "<string>",
"recordingEnabled": true,
"firstSpeakerSettings": {
"user": {
"fallback": {
"delay": "<string>",
"text": "<string>",
"prompt": "<string>"
}
},
"agent": {
"uninterruptible": true,
"text": "<string>",
"prompt": "<string>",
"delay": "<string>"
}
},
"dataConnection": {
"websocketUrl": "<string>",
"audioConfig": {
"sampleRate": 123
},
"dataMessages": {
"pong": true,
"state": true,
"transcript": true,
"clientToolInvocation": true,
"dataConnectionToolInvocation": true,
"playbackClearBuffer": true,
"callStarted": true,
"debug": true,
"callEvent": true,
"toolUsed": true,
"userStartedSpeaking": true,
"userStoppedSpeaking": true,
"invokingTool": true
},
"headers": {}
},
"experimentalSettings": {},
"callbacks": {
"joined": {
"url": "<string>",
"secrets": [
"<string>"
]
},
"ended": {
"url": "<string>",
"secrets": [
"<string>"
]
},
"billed": {
"url": "<string>",
"secrets": [
"<string>"
]
}
},
"voice": "<string>",
"voiceOverrides": {
"elevenLabs": {
"voiceId": "<string>",
"model": "<string>",
"speed": 123,
"useSpeakerBoost": true,
"style": 123,
"similarityBoost": 123,
"stability": 123,
"pronunciationDictionaries": [
{
"dictionaryId": "<string>",
"versionId": "<string>"
}
],
"optimizeStreamingLatency": 123,
"maxSampleRate": 123
},
"cartesia": {
"voiceId": "<string>",
"model": "<string>",
"speed": 123,
"emotion": "<string>",
"emotions": [
"<string>"
],
"generationConfig": {
"volume": 123,
"speed": 123,
"emotion": "<string>",
"pronunciationDictId": "<string>"
}
},
"lmnt": {
"voiceId": "<string>",
"model": "<string>",
"speed": 123,
"conversational": true
},
"google": {
"voiceId": "<string>",
"speakingRate": 123
},
"inworld": {
"voiceId": "<string>",
"modelId": "<string>",
"speakingRate": 123,
"temperature": 123,
"applyTextNormalization": true
},
"respeecher": {
"voiceId": "<string>",
"model": "<string>",
"seed": 123,
"temperature": 123,
"topK": 123,
"topP": 123,
"minP": 123,
"presencePenalty": 123,
"repetitionPenalty": 123,
"frequencyPenalty": 123
},
"generic": {
"url": "<string>",
"headers": {},
"body": {},
"responseSampleRate": 123,
"responseWordsPerMinute": 123,
"responseMimeType": "<string>",
"jsonAudioFieldPath": "<string>"
}
},
"toolOverrides": {
"remove": [
"<string>"
],
"removeAll": true,
"add": [
{
"toolId": "<string>",
"toolName": "<string>",
"temporaryTool": {
"modelToolName": "<string>",
"description": "<string>",
"dynamicParameters": [
{
"name": "<string>",
"schema": {},
"required": true
}
],
"staticParameters": [
{
"name": "<string>",
"value": "<unknown>"
}
],
"automaticParameters": [
{
"name": "<string>"
}
],
"requirements": {
"httpSecurityOptions": {
"options": [
{
"requirements": {},
"ultravoxCallTokenRequirement": {
"scopes": [
"<string>"
]
}
}
]
},
"requiredParameterOverrides": [
"<string>"
]
},
"timeout": "<string>",
"precomputable": true,
"http": {
"baseUrlPattern": "<string>",
"httpMethod": "<string>"
},
"client": {},
"dataConnection": {},
"staticResponse": {
"responseText": "<string>"
}
},
"nameOverride": "<string>",
"descriptionOverride": "<string>",
"authTokens": {},
"parameterOverrides": {},
"transitionId": "<string>"
}
]
},
"sharedSecrets": [
"<string>"
],
"agentId": "<string>"
},
"startCall": {
"systemPrompt": "<string>",
"temperature": 123,
"model": "<string>",
"voice": "<string>",
"externalVoice": {
"elevenLabs": {
"voiceId": "<string>",
"model": "<string>",
"speed": 123,
"useSpeakerBoost": true,
"style": 123,
"similarityBoost": 123,
"stability": 123,
"pronunciationDictionaries": [
{
"dictionaryId": "<string>",
"versionId": "<string>"
}
],
"optimizeStreamingLatency": 123,
"maxSampleRate": 123
},
"cartesia": {
"voiceId": "<string>",
"model": "<string>",
"speed": 123,
"emotion": "<string>",
"emotions": [
"<string>"
],
"generationConfig": {
"volume": 123,
"speed": 123,
"emotion": "<string>",
"pronunciationDictId": "<string>"
}
},
"lmnt": {
"voiceId": "<string>",
"model": "<string>",
"speed": 123,
"conversational": true
},
"google": {
"voiceId": "<string>",
"speakingRate": 123
},
"inworld": {
"voiceId": "<string>",
"modelId": "<string>",
"speakingRate": 123,
"temperature": 123,
"applyTextNormalization": true
},
"respeecher": {
"voiceId": "<string>",
"model": "<string>",
"seed": 123,
"temperature": 123,
"topK": 123,
"topP": 123,
"minP": 123,
"presencePenalty": 123,
"repetitionPenalty": 123,
"frequencyPenalty": 123
},
"generic": {
"url": "<string>",
"headers": {},
"body": {},
"responseSampleRate": 123,
"responseWordsPerMinute": 123,
"responseMimeType": "<string>",
"jsonAudioFieldPath": "<string>"
}
},
"languageHint": "<string>",
"initialMessages": [
{
"text": "<string>",
"invocationId": "<string>",
"toolName": "<string>",
"errorDetails": "<string>",
"callStageMessageIndex": 123,
"callStageId": "<string>",
"callState": {},
"timespan": {
"start": "<string>",
"end": "<string>"
},
"wallClockTimespan": {
"start": "<string>",
"end": "<string>"
},
"metadata": {}
}
],
"joinTimeout": "<string>",
"maxDuration": "<string>",
"timeExceededMessage": "<string>",
"inactivityMessages": [
{
"duration": "<string>",
"message": "<string>"
}
],
"selectedTools": [
{
"toolId": "<string>",
"toolName": "<string>",
"temporaryTool": {
"modelToolName": "<string>",
"description": "<string>",
"dynamicParameters": [
{
"name": "<string>",
"schema": {},
"required": true
}
],
"staticParameters": [
{
"name": "<string>",
"value": "<unknown>"
}
],
"automaticParameters": [
{
"name": "<string>"
}
],
"requirements": {
"httpSecurityOptions": {
"options": [
{
"requirements": {},
"ultravoxCallTokenRequirement": {
"scopes": [
"<string>"
]
}
}
]
},
"requiredParameterOverrides": [
"<string>"
]
},
"timeout": "<string>",
"precomputable": true,
"http": {
"baseUrlPattern": "<string>",
"httpMethod": "<string>"
},
"client": {},
"dataConnection": {},
"staticResponse": {
"responseText": "<string>"
}
},
"nameOverride": "<string>",
"descriptionOverride": "<string>",
"authTokens": {},
"parameterOverrides": {},
"transitionId": "<string>"
}
],
"medium": {
"webRtc": {
"dataMessages": {
"pong": true,
"state": true,
"transcript": true,
"clientToolInvocation": true,
"dataConnectionToolInvocation": true,
"playbackClearBuffer": true,
"callStarted": true,
"debug": true,
"callEvent": true,
"toolUsed": true,
"userStartedSpeaking": true,
"userStoppedSpeaking": true,
"invokingTool": true
}
},
"twilio": {
"outgoing": {
"to": "<string>",
"from": "<string>",
"additionalParams": {}
},
"dtmfHandling": {
"ignore": true,
"userTextMessage": {
"text": "<string>"
}
}
},
"serverWebSocket": {
"inputSampleRate": 123,
"outputSampleRate": 123,
"clientBufferSizeMs": 123,
"dataMessages": {
"pong": true,
"state": true,
"transcript": true,
"clientToolInvocation": true,
"dataConnectionToolInvocation": true,
"playbackClearBuffer": true,
"callStarted": true,
"debug": true,
"callEvent": true,
"toolUsed": true,
"userStartedSpeaking": true,
"userStoppedSpeaking": true,
"invokingTool": true
},
"mediaIdleTimeout": "<string>"
},
"telnyx": {
"outgoing": {
"to": "<string>",
"from": "<string>",
"additionalParams": {}
},
"dtmfHandling": {
"ignore": true,
"userTextMessage": {
"text": "<string>"
}
}
},
"plivo": {
"outgoing": {
"to": "<string>",
"from": "<string>",
"additionalParams": {}
},
"dtmfHandling": {
"ignore": true,
"userTextMessage": {
"text": "<string>"
}
}
},
"exotel": {
"dtmfHandling": {
"ignore": true,
"userTextMessage": {
"text": "<string>"
}
}
},
"sip": {
"incoming": {},
"outgoing": {
"to": "<string>",
"from": "<string>",
"username": "<string>",
"password": "<string>"
}
}
},
"recordingEnabled": true,
"transcriptOptional": true,
"vadSettings": {
"turnEndpointDelay": "<string>",
"minimumTurnDuration": "<string>",
"minimumInterruptionDuration": "<string>",
"frameActivationThreshold": 123
},
"firstSpeakerSettings": {
"user": {
"fallback": {
"delay": "<string>",
"text": "<string>",
"prompt": "<string>"
}
},
"agent": {
"uninterruptible": true,
"text": "<string>",
"prompt": "<string>",
"delay": "<string>"
}
},
"experimentalSettings": {},
"metadata": {},
"initialState": {},
"dataConnection": {
"websocketUrl": "<string>",
"audioConfig": {
"sampleRate": 123
},
"dataMessages": {
"pong": true,
"state": true,
"transcript": true,
"clientToolInvocation": true,
"dataConnectionToolInvocation": true,
"playbackClearBuffer": true,
"callStarted": true,
"debug": true,
"callEvent": true,
"toolUsed": true,
"userStartedSpeaking": true,
"userStoppedSpeaking": true,
"invokingTool": true
},
"headers": {}
},
"callbacks": {
"joined": {
"url": "<string>",
"secrets": [
"<string>"
]
},
"ended": {
"url": "<string>",
"secrets": [
"<string>"
]
},
"billed": {
"url": "<string>",
"secrets": [
"<string>"
]
}
},
"voiceOverrides": {
"elevenLabs": {
"voiceId": "<string>",
"model": "<string>",
"speed": 123,
"useSpeakerBoost": true,
"style": 123,
"similarityBoost": 123,
"stability": 123,
"pronunciationDictionaries": [
{
"dictionaryId": "<string>",
"versionId": "<string>"
}
],
"optimizeStreamingLatency": 123,
"maxSampleRate": 123
},
"cartesia": {
"voiceId": "<string>",
"model": "<string>",
"speed": 123,
"emotion": "<string>",
"emotions": [
"<string>"
],
"generationConfig": {
"volume": 123,
"speed": 123,
"emotion": "<string>",
"pronunciationDictId": "<string>"
}
},
"lmnt": {
"voiceId": "<string>",
"model": "<string>",
"speed": 123,
"conversational": true
},
"google": {
"voiceId": "<string>",
"speakingRate": 123
},
"inworld": {
"voiceId": "<string>",
"modelId": "<string>",
"speakingRate": 123,
"temperature": 123,
"applyTextNormalization": true
},
"respeecher": {
"voiceId": "<string>",
"model": "<string>",
"seed": 123,
"temperature": 123,
"topK": 123,
"topP": 123,
"minP": 123,
"presencePenalty": 123,
"repetitionPenalty": 123,
"frequencyPenalty": 123
},
"generic": {
"url": "<string>",
"headers": {},
"body": {},
"responseSampleRate": 123,
"responseWordsPerMinute": 123,
"responseMimeType": "<string>",
"jsonAudioFieldPath": "<string>"
}
},
"sharedSecrets": [
"<string>"
]
},
"reject": {
"sipRejectCode": 123,
"message": "<string>"
}
}