Telnyx Voice - Java
Installation
<!-- Maven --> <dependency> <groupId>com.telnyx.sdk</groupId> <artifactId>telnyx-java</artifactId> <version>6.29.0</version> </dependency>
// Gradle implementation("com.telnyx.sdk:telnyx-java:6.29.0")
Setup
import com.telnyx.sdk.client.TelnyxClient; import com.telnyx.sdk.client.okhttp.TelnyxOkHttpClient;
TelnyxClient client = TelnyxOkHttpClient.fromEnv();
All examples below assume client is already initialized as shown above.
Error Handling
All API calls can fail with network errors, rate limits (429), validation errors (422), or authentication errors (401). Always handle errors in production code:
import com.telnyx.sdk.models.calls.CallDialParams; import com.telnyx.sdk.models.calls.CallDialResponse; CallDialParams params = CallDialParams.builder() .connectionId("7267xxxxxxxxxxxxxx") .from("+18005550101") .to("+18005550100") .build(); CallDialResponse response = client.calls().dial(params);
Common error codes: 401 invalid API key, 403 insufficient permissions, 404 resource not found, 422 validation error (check field formats), 429 rate limited (retry with exponential backoff).
Important Notes
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Phone numbers must be in E.164 format (e.g., +13125550001 ). Include the + prefix and country code. No spaces, dashes, or parentheses.
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Pagination: List methods return a page. Use .autoPager() for automatic iteration: for (var item : page.autoPager()) { ... } . For manual control, use .hasNextPage() and .nextPage() .
Operational Caveats
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Call Control is event-driven. After dial() or an inbound webhook, issue follow-up commands from webhook handlers using the call_control_id in the event payload.
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Outbound and inbound flows are different: outbound calls start with dial() , while inbound calls must be answered from the incoming webhook before other commands run.
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A publicly reachable webhook endpoint is required for real call control. Without it, calls may connect but your application cannot drive the live call state.
Reference Use Rules
Do not invent Telnyx parameters, enums, response fields, or webhook fields.
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If the parameter, enum, or response field you need is not shown inline in this skill, read references/api-details.md before writing code.
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Before using any operation in ## Additional Operations , read the optional-parameters section and the response-schemas section.
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Before reading or matching webhook fields beyond the inline examples, read the webhook payload reference.
Core Tasks
Dial an outbound call
Primary voice entrypoint. Agents need the async call-control identifiers returned here.
client.calls().dial() — POST /calls
Parameter Type Required Description
to
string (E.164) Yes The DID or SIP URI to dial out to.
from
string (E.164) Yes The from number to be used as the caller id presented to t...
connectionId
string (UUID) Yes The ID of the Call Control App (formerly ID of the connectio...
timeoutSecs
integer No The number of seconds that Telnyx will wait for the call to ...
billingGroupId
string (UUID) No Use this field to set the Billing Group ID for the call.
clientState
string No Use this field to add state to every subsequent webhook.
...
+48 optional params in references/api-details.md
import com.telnyx.sdk.models.calls.CallDialParams; import com.telnyx.sdk.models.calls.CallDialResponse;
CallDialParams params = CallDialParams.builder() .connectionId("7267xxxxxxxxxxxxxx") .from("+18005550101") .to("+18005550100") .build(); CallDialResponse response = client.calls().dial(params);
Primary response fields:
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response.data.callControlId
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response.data.callLegId
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response.data.callSessionId
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response.data.isAlive
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response.data.recordingId
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response.data.callDuration
Answer an inbound call
Primary inbound call-control command.
client.calls().actions().answer() — POST /calls/{call_control_id}/actions/answer
Parameter Type Required Description
callControlId
string (UUID) Yes Unique identifier and token for controlling the call
billingGroupId
string (UUID) No Use this field to set the Billing Group ID for the call.
clientState
string No Use this field to add state to every subsequent webhook.
webhookUrl
string (URL) No Use this field to override the URL for which Telnyx will sen...
...
+26 optional params in references/api-details.md
import com.telnyx.sdk.models.calls.actions.ActionAnswerParams; import com.telnyx.sdk.models.calls.actions.ActionAnswerResponse;
ActionAnswerResponse response = client.calls().actions().answer("v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ");
Primary response fields:
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response.data.result
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response.data.recordingId
Transfer a live call
Common post-answer control path with downstream webhook implications.
client.calls().actions().transfer() — POST /calls/{call_control_id}/actions/transfer
Parameter Type Required Description
to
string (E.164) Yes The DID or SIP URI to dial out to.
callControlId
string (UUID) Yes Unique identifier and token for controlling the call
timeoutSecs
integer No The number of seconds that Telnyx will wait for the call to ...
clientState
string No Use this field to add state to every subsequent webhook.
webhookUrl
string (URL) No Use this field to override the URL for which Telnyx will sen...
...
+33 optional params in references/api-details.md
import com.telnyx.sdk.models.calls.actions.ActionTransferParams; import com.telnyx.sdk.models.calls.actions.ActionTransferResponse;
ActionTransferParams params = ActionTransferParams.builder() .callControlId("v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ") .to("+18005550100") .build(); ActionTransferResponse response = client.calls().actions().transfer(params);
Primary response fields:
- response.data.result
Webhook Verification
Telnyx signs webhooks with Ed25519. Each request includes telnyx-signature-ed25519
and telnyx-timestamp headers. Always verify signatures in production:
import com.telnyx.sdk.core.UnwrapWebhookParams; import com.telnyx.sdk.core.http.Headers;
// In your webhook handler (e.g., Spring — use raw body): @PostMapping("/webhooks") public ResponseEntity<String> handleWebhook( @RequestBody String payload, HttpServletRequest request) { try { Headers headers = Headers.builder() .put("telnyx-signature-ed25519", request.getHeader("telnyx-signature-ed25519")) .put("telnyx-timestamp", request.getHeader("telnyx-timestamp")) .build(); var event = client.webhooks().unwrap( UnwrapWebhookParams.builder() .body(payload) .headers(headers) .build()); // Signature valid — process the event System.out.println("Received webhook event"); return ResponseEntity.ok("OK"); } catch (Exception e) { System.err.println("Webhook verification failed: " + e.getMessage()); return ResponseEntity.badRequest().body("Invalid signature"); } }
Webhooks
These webhook payload fields are inline because they are part of the primary integration path.
Call Answered
Field Type Description
data.record_type
enum: event Identifies the type of the resource.
data.event_type
enum: call.answered The type of event being delivered.
data.id
uuid Identifies the type of resource.
data.occurred_at
date-time ISO 8601 datetime of when the event occurred.
data.payload.call_control_id
string Call ID used to issue commands via Call Control API.
data.payload.connection_id
string Call Control App ID (formerly Telnyx connection ID) used in the call.
data.payload.call_leg_id
string ID that is unique to the call and can be used to correlate webhook events.
data.payload.call_session_id
string ID that is unique to the call session and can be used to correlate webhook ev...
Call Hangup
Field Type Description
data.record_type
enum: event Identifies the type of the resource.
data.event_type
enum: call.hangup The type of event being delivered.
data.id
uuid Identifies the type of resource.
data.occurred_at
date-time ISO 8601 datetime of when the event occurred.
data.payload.call_control_id
string Call ID used to issue commands via Call Control API.
data.payload.connection_id
string Call Control App ID (formerly Telnyx connection ID) used in the call.
data.payload.call_leg_id
string ID that is unique to the call and can be used to correlate webhook events.
data.payload.call_session_id
string ID that is unique to the call session and can be used to correlate webhook ev...
Call Initiated
Field Type Description
data.record_type
enum: event Identifies the type of the resource.
data.event_type
enum: call.initiated The type of event being delivered.
data.id
uuid Identifies the type of resource.
data.occurred_at
date-time ISO 8601 datetime of when the event occurred.
data.payload.call_control_id
string Call ID used to issue commands via Call Control API.
data.payload.connection_id
string Call Control App ID (formerly Telnyx connection ID) used in the call.
data.payload.connection_codecs
string The list of comma-separated codecs enabled for the connection.
data.payload.offered_codecs
string The list of comma-separated codecs offered by caller.
If you need webhook fields that are not listed inline here, read the webhook payload reference before writing the handler.
Important Supporting Operations
Use these when the core tasks above are close to your flow, but you need a common variation or follow-up step.
Hangup call
End a live call from your webhook-driven control flow.
client.calls().actions().hangup() — POST /calls/{call_control_id}/actions/hangup
Parameter Type Required Description
callControlId
string (UUID) Yes Unique identifier and token for controlling the call
clientState
string No Use this field to add state to every subsequent webhook.
commandId
string (UUID) No Use this field to avoid duplicate commands.
customHeaders
array[object] No Custom headers to be added to the SIP BYE message.
import com.telnyx.sdk.models.calls.actions.ActionHangupParams; import com.telnyx.sdk.models.calls.actions.ActionHangupResponse;
ActionHangupResponse response = client.calls().actions().hangup("v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ");
Primary response fields:
- response.data.result
Bridge calls
Trigger a follow-up action in an existing workflow rather than creating a new top-level resource.
client.calls().actions().bridge() — POST /calls/{call_control_id}/actions/bridge
Parameter Type Required Description
callControlId
string (UUID) Yes The Call Control ID of the call you want to bridge with, can...
callControlId
string (UUID) Yes Unique identifier and token for controlling the call
clientState
string No Use this field to add state to every subsequent webhook.
commandId
string (UUID) No Use this field to avoid duplicate commands.
videoRoomId
string (UUID) No The ID of the video room you want to bridge with, can't be u...
...
+16 optional params in references/api-details.md
import com.telnyx.sdk.models.calls.actions.ActionBridgeParams; import com.telnyx.sdk.models.calls.actions.ActionBridgeResponse;
ActionBridgeParams params = ActionBridgeParams.builder() .callControlIdToBridge("v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ") .callControlId("v3:MdI91X4lWFEs7IgbBEOT9M4AigoY08M0WWZFISt1Yw2axZ_IiE4pqg") .build(); ActionBridgeResponse response = client.calls().actions().bridge(params);
Primary response fields:
- response.data.result
Reject a call
Trigger a follow-up action in an existing workflow rather than creating a new top-level resource.
client.calls().actions().reject() — POST /calls/{call_control_id}/actions/reject
Parameter Type Required Description
cause
enum (CALL_REJECTED, USER_BUSY) Yes Cause for call rejection.
callControlId
string (UUID) Yes Unique identifier and token for controlling the call
clientState
string No Use this field to add state to every subsequent webhook.
commandId
string (UUID) No Use this field to avoid duplicate commands.
import com.telnyx.sdk.models.calls.actions.ActionRejectParams; import com.telnyx.sdk.models.calls.actions.ActionRejectResponse;
ActionRejectParams params = ActionRejectParams.builder() .callControlId("v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ") .cause(ActionRejectParams.Cause.USER_BUSY) .build(); ActionRejectResponse response = client.calls().actions().reject(params);
Primary response fields:
- response.data.result
Retrieve a call status
Fetch the current state before updating, deleting, or making control-flow decisions.
client.calls().retrieveStatus() — GET /calls/{call_control_id}
Parameter Type Required Description
callControlId
string (UUID) Yes Unique identifier and token for controlling the call
import com.telnyx.sdk.models.calls.CallRetrieveStatusParams; import com.telnyx.sdk.models.calls.CallRetrieveStatusResponse;
CallRetrieveStatusResponse response = client.calls().retrieveStatus("v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ");
Primary response fields:
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response.data.callControlId
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response.data.callDuration
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response.data.callLegId
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response.data.callSessionId
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response.data.clientState
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response.data.endTime
List all active calls for given connection
Fetch the current state before updating, deleting, or making control-flow decisions.
client.connections().listActiveCalls() — GET /connections/{connection_id}/active_calls
Parameter Type Required Description
connectionId
string (UUID) Yes Telnyx connection id
page
object No Consolidated page parameter (deepObject style).
import com.telnyx.sdk.models.connections.ConnectionListActiveCallsPage; import com.telnyx.sdk.models.connections.ConnectionListActiveCallsParams;
ConnectionListActiveCallsPage page = client.connections().listActiveCalls("1293384261075731461");
Response wrapper:
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items: page.data
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pagination: page.meta
Primary item fields:
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callControlId
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callDuration
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callLegId
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callSessionId
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clientState
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recordType
List call control applications
Inspect available resources or choose an existing resource before mutating it.
client.callControlApplications().list() — GET /call_control_applications
Parameter Type Required Description
sort
enum (created_at, connection_name, active) No Specifies the sort order for results.
filter
object No Consolidated filter parameter (deepObject style).
page
object No Consolidated page parameter (deepObject style).
import com.telnyx.sdk.models.callcontrolapplications.CallControlApplicationListPage; import com.telnyx.sdk.models.callcontrolapplications.CallControlApplicationListParams;
CallControlApplicationListPage page = client.callControlApplications().list();
Response wrapper:
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items: page.data
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pagination: page.meta
Primary item fields:
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id
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createdAt
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updatedAt
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active
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anchorsiteOverride
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applicationName
Additional Operations
Use the core tasks above first. The operations below are indexed here with exact SDK methods and required params; use references/api-details.md for full optional params, response schemas, and lower-frequency webhook payloads. Before using any operation below, read the optional-parameters section and the response-schemas section so you do not guess missing fields.
Operation SDK method Endpoint Use when Required params
Create a call control application client.callControlApplications().create()
POST /call_control_applications
Create or provision an additional resource when the core tasks do not cover this flow. applicationName , webhookEventUrl
Retrieve a call control application client.callControlApplications().retrieve()
GET /call_control_applications/{id}
Fetch the current state before updating, deleting, or making control-flow decisions. id
Update a call control application client.callControlApplications().update()
PATCH /call_control_applications/{id}
Modify an existing resource without recreating it. applicationName , webhookEventUrl , id
Delete a call control application client.callControlApplications().delete()
DELETE /call_control_applications/{id}
Remove, detach, or clean up an existing resource. id
SIP Refer a call client.calls().actions().refer()
POST /calls/{call_control_id}/actions/refer
Trigger a follow-up action in an existing workflow rather than creating a new top-level resource. sipAddress , callControlId
Send SIP info client.calls().actions().sendSipInfo()
POST /calls/{call_control_id}/actions/send_sip_info
Trigger a follow-up action in an existing workflow rather than creating a new top-level resource. contentType , body , callControlId
Other Webhook Events
Event data.event_type
Description
callBridged
call.bridged
Call Bridged
For exhaustive optional parameters, full response schemas, and complete webhook payloads, see references/api-details.md.