Telnyx Voice Python

Telnyx Voice - Python

Installation

pip install telnyx

Setup

import os
from telnyx import Telnyx

client = Telnyx(
    api_key=os.environ.get("TELNYX_API_KEY"),  # This is the default and can be omitted
)

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 telnyx

try:
    response = client.calls.dial(
        connection_id="7267xxxxxxxxxxxxxx",
        from_="+18005550101",
        to="+18005550100;secure=srtp",
    )
except telnyx.APIConnectionError:
    print("Network error — check connectivity and retry")
except telnyx.RateLimitError:
    import time
    time.sleep(1)  # Check Retry-After header for actual delay
except telnyx.APIStatusError as e:
    print(f"API error {e.status_code}: {e.message}")
    if e.status_code == 422:
        print("Validation error — check required fields and formats")

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

• Phone numbers must be in E.164 format (e.g., +13125550001). Include the + prefix and country code. No spaces, dashes, or parentheses.
• Pagination: List methods return an auto-paginating iterator. Use for item in page_result: to iterate through all pages automatically.

Operational Caveats

• 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.
• 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.
• 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.

• If the parameter, enum, or response field you need is not shown inline in this skill, read references/api-details.md before writing code.
• Before using any operation in ## Additional Operations, read the optional-parameters section and the response-schemas section.
• 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

response = client.calls.dial(
    connection_id="7267xxxxxxxxxxxxxx",
    from_="+18005550101",
    to="+18005550100;secure=srtp",
)
print(response.data)

Primary response fields:

• response.data.call_control_id
• response.data.call_leg_id
• response.data.call_session_id
• response.data.is_alive
• response.data.recording_id
• response.data.call_duration

Answer an inbound call

Primary inbound call-control command.

client.calls.actions.answer() — POST /calls/{call_control_id}/actions/answer

response = client.calls.actions.answer(
    call_control_id="550e8400-e29b-41d4-a716-446655440000",
)
print(response.data)

Primary response fields:

• response.data.result
• response.data.recording_id

Transfer a live call

Common post-answer control path with downstream webhook implications.

client.calls.actions.transfer() — POST /calls/{call_control_id}/actions/transfer

response = client.calls.actions.transfer(
    call_control_id="550e8400-e29b-41d4-a716-446655440000",
    to="+18005550100;secure=srtp",
)
print(response.data)

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:

# In your webhook handler (e.g., Flask — use raw body, not parsed JSON):
@app.route("/webhooks", methods=["POST"])
def handle_webhook():
    payload = request.get_data(as_text=True)  # raw body as string
    headers = dict(request.headers)
    try:
        event = client.webhooks.unwrap(payload, headers=headers)
    except Exception as e:
        print(f"Webhook verification failed: {e}")
        return "Invalid signature", 400
    # Signature valid — event is the parsed webhook payload
    print(f"Received event: {event.data.event_type}")
    return "OK", 200

Webhooks

These webhook payload fields are inline because they are part of the primary integration path.

Call Answered

Call Hangup

Call Initiated

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

response = client.calls.actions.hangup(
    call_control_id="550e8400-e29b-41d4-a716-446655440000",
)
print(response.data)

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

response = client.calls.actions.bridge(
    call_control_id_to_bridge="call_control_id",
    call_control_id_to_bridge_with="v3:MdI91X4lWFEs7IgbBEOT9M4AigoY08M0WWZFISt1Yw2axZ_IiE4pqg",
)
print(response.data)

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

response = client.calls.actions.reject(
    call_control_id="550e8400-e29b-41d4-a716-446655440000",
    cause="USER_BUSY",
)
print(response.data)

Primary response fields:

• response.data.result

Retrieve a call status

Fetch the current state before updating, deleting, or making control-flow decisions.

client.calls.retrieve_status() — GET /calls/{call_control_id}

response = client.calls.retrieve_status(
    "call_control_id",
)
print(response.data)

Primary response fields:

• response.data.call_control_id
• response.data.call_duration
• response.data.call_leg_id
• response.data.call_session_id
• response.data.client_state
• response.data.end_time

List all active calls for given connection

Fetch the current state before updating, deleting, or making control-flow decisions.

client.connections.list_active_calls() — GET /connections/{connection_id}/active_calls

page = client.connections.list_active_calls(
    connection_id="1293384261075731461",
)
page = page.data[0]
print(page.call_control_id)

Response wrapper:

• items: page.data
• pagination: page.meta

Primary item fields:

• call_control_id
• call_duration
• call_leg_id
• call_session_id
• client_state
• record_type

List call control applications

Inspect available resources or choose an existing resource before mutating it.

client.call_control_applications.list() — GET /call_control_applications

page = client.call_control_applications.list()
page = page.data[0]
print(page.id)

Response wrapper:

• items: page.data
• pagination: page.meta

Primary item fields:

• id
• created_at
• updated_at
• active
• anchorsite_override
• application_name

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.

Other Webhook Events

For exhaustive optional parameters, full response schemas, and complete webhook payloads, see references/api-details.md.