Agent Skills
› fanfan-de/anybox
› twilio-voice-outbound-calls
twilio-voice-outbound-calls
GitHub通过Twilio Programmable Voice API发起外呼，支持基础通话、AMD、会议桥接、录音及SIP中继。涵盖合规要求、环境配置及Python/Node.js快速入门代码示例。
Trigger Scenarios
需要发起电话外呼
询问Twilio语音API功能
构建销售拨号器或自动外呼系统
Install
npx skills add fanfan-de/anybox --skill twilio-voice-outbound-calls -g -y
SKILL.md
Frontmatter
{
"name": "twilio-voice-outbound-calls",
"description": "Make outbound phone calls via Twilio's Programmable Voice REST API. Covers the full voice platform: calls.create(), answering machine detection (AMD), conference-based agent bridging, call recording, status tracking, and SIP Trunking. Use this skill for outbound calls, sales dialers, or when asking what voice APIs are available."
}
Overview
Agent safety: Before placing an outbound call, always confirm the recipient number and intent with the user. Outbound calls are irreversible and may incur charges. For automated systems, implement TCPA compliance: obtain prior express consent, respect quiet hours (8 AM–9 PM recipient local time), and maintain a Do Not Call list.
Every outbound call requires a from Twilio number, a to recipient, and TwiML instructions that define what happens when the call is answered — either as a webhook URL or inline.
Voice Platform Capabilities
Outbound calls go beyond basic calls.create(). Here's what you can build:
| Capability | How | When to use |
|---|---|---|
| Basic outbound call | calls.create() with TwiML or webhook URL |
Any outbound call — see Quickstart below |
| Answering Machine Detection (AMD) | machineDetection parameter on calls.create() |
Sales dialers, call campaigns — filter voicemail from humans |
| Conference-based agent bridging | <Dial><Conference> in TwiML |
Connect agents to live prospects with whisper, barge, hold |
| SIP Trunking | Elastic SIP Trunking | Bring your own carrier for outbound calls — cost reduction at scale |
| Call Recording | record=True on calls.create() or <Record> verb |
Compliance, QA, training |
| Voice Insights | Automatic per-call metrics | Call quality monitoring — latency, jitter, packet loss, answer rates |
| AI Voice Agents | ConversationRelay + LLM | Real-time speech recognition → LLM → TTS for conversational AI |
For TwiML verbs (Say, Gather, Dial, Record, Conference, Pay), see twilio-voice-twiml.
For AI voice agents, see twilio-voice-conversation-relay.
Prerequisites
- Twilio account with a voice-capable phone number
— New to Twilio? See
twilio-account-setupfor signup, getting a number, and trial limitations — Trial accounts can only call verified numbers - Environment variables:
TWILIO_ACCOUNT_SIDTWILIO_AUTH_TOKEN— Seetwilio-iam-auth-setupfor credential setup and best practices
- SDK:
pip install twilio/npm install twilio
Quickstart
Python
import os
from twilio.rest import Client
client = Client(os.environ["TWILIO_ACCOUNT_SID"], os.environ["TWILIO_AUTH_TOKEN"])
call = client.calls.create(
from_="+15017122661", # Your Twilio number (E.164)
to="+15558675310", # Recipient (E.164)
twiml="<Response><Say>Your order has shipped. Goodbye.</Say></Response>"
)
print(call.sid) # CAxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
print(call.status) # queued | ringing | in-progress | completed | failed
Node.js
const twilio = require("twilio");
const client = twilio(process.env.TWILIO_ACCOUNT_SID, process.env.TWILIO_AUTH_TOKEN);
const call = await client.calls.create({
from: "+15017122661",
to: "+15558675310",
twiml: "<Response><Say>Your order has shipped. Goodbye.</Say></Response>",
});
console.log(call.sid);
console.log(call.status);
Key Patterns
Use a Webhook URL for Dynamic Call Handling
Pass a url instead of inline twiml — Twilio POSTs to your server when the call connects and executes the TwiML you return.
Python
call = client.calls.create(
from_="+15017122661",
to="+15558675310",
url="https://yourapp.com/twiml/welcome"
)
Node.js
const call = await client.calls.create({
from: "+15017122661",
to: "+15558675310",
url: "https://yourapp.com/twiml/welcome",
});
Python (Flask) — TwiML webhook handler
from flask import Flask
from twilio.twiml.voice_response import VoiceResponse
app = Flask(__name__)
@app.route("/twiml/welcome", methods=["POST"])
def welcome():
response = VoiceResponse()
response.say("Hello! Press 1 to hear your account balance.")
response.gather(num_digits=1, action="/twiml/handle-input")
return str(response)
Node.js (Express) — TwiML webhook handler
const { VoiceResponse } = require("twilio").twiml;
app.post("/twiml/welcome", (req, res) => {
const response = new VoiceResponse();
response.say("Hello! Press 1 to hear your account balance.");
response.gather({ numDigits: 1, action: "/twiml/handle-input" });
res.type("text/xml").send(response.toString());
});
For all TwiML verbs (Say, Gather, Dial, Record, Conference), see twilio-voice-twiml.
Track Call Status
Python
call = client.calls.create(
from_="+15017122661",
to="+15558675310",
url="https://yourapp.com/twiml/welcome",
status_callback="https://yourapp.com/call-status",
status_callback_method="POST"
)
Node.js
const call = await client.calls.create({
from: "+15017122661",
to: "+15558675310",
url: "https://yourapp.com/twiml/welcome",
statusCallback: "https://yourapp.com/call-status",
statusCallbackMethod: "POST",
});
Status transitions: queued → ringing → in-progress → completed (or failed/busy/no-answer).
Record a Call
Python
call = client.calls.create(
from_="+15017122661",
to="+15558675310",
url="https://yourapp.com/twiml/welcome",
record=True,
recording_status_callback="https://yourapp.com/recording-ready"
)
Node.js
const call = await client.calls.create({
from: "+15017122661",
to: "+15558675310",
url: "https://yourapp.com/twiml/welcome",
record: true,
recordingStatusCallback: "https://yourapp.com/recording-ready",
});
Recordings accessible at https://api.twilio.com/2010-04-01/Accounts/{AccountSid}/Recordings.
Answering Machine Detection (AMD)
Detect whether a human or voicemail answers before connecting an agent or leaving a message. Two modes:
| Mode | Behavior | Best for |
|---|---|---|
Enable |
Returns result immediately when human/machine first detected | Sales dialers — connect agent to humans ASAP |
DetectMessageEnd |
Waits for voicemail greeting to finish (beep/silence) | Leaving voicemail — wait for beep, then play/record message |
Python — Sales dialer (connect agents to live answers only)
call = client.calls.create(
from_="+15017122661",
to="+15558675310",
url="https://yourapp.com/handle-answer",
machine_detection="Enable", # Immediate detection — use for live-agent connect
async_amd=True, # Non-blocking — call connects while AMD analyzes
async_amd_status_callback="https://yourapp.com/amd-result",
async_amd_status_callback_method="POST"
)
Node.js
const call = await client.calls.create({
from: "+15017122661",
to: "+15558675310",
url: "https://yourapp.com/handle-answer",
machineDetection: "Enable",
asyncAmd: true,
asyncAmdStatusCallback: "https://yourapp.com/amd-result",
asyncAmdStatusCallbackMethod: "POST",
});
AMD webhook delivers AnsweredBy parameter:
| Value | Meaning | Action |
|---|---|---|
human |
Live person detected | Connect to agent |
machine_start |
Machine detected, greeting still playing | Hang up or wait |
machine_end_beep |
Voicemail beep heard | Leave message |
machine_end_silence |
Silence after greeting | Leave message |
fax |
Fax tone detected | Hang up |
unknown |
Could not determine | Treat as human or retry |
Conference-based agent bridging (production pattern for sales dialers):
# In /handle-answer webhook — when AMD says "human":
response = VoiceResponse()
dial = response.dial()
dial.conference(
f"Sales-{call_sid}",
start_conference_on_enter=False, # Prospect waits for agent
end_conference_on_exit=True
)
# Separately, dial agent into same conference:
client.calls.create(
from_="+15017122661",
to=agent_number,
twiml=f'<Response><Dial><Conference startConferenceOnEnter="true">Sales-{call_sid}</Conference></Dial></Response>'
)
This pattern gives you call control (whisper to agent before connecting, supervisor barge-in, hold) that direct <Dial> does not.
Cost: AMD adds ~$0.0075 per call to standard voice pricing.
Response Fields
| Field | Description |
|---|---|
sid |
Call identifier (CA...) |
status |
queued, ringing, in-progress, completed, failed, busy, no-answer |
duration |
Length in seconds (after completion) |
price |
Cost (populated after completion) |
Common Errors
| Code | Meaning | Fix |
|---|---|---|
| 21211 | Invalid to number |
Validate E.164 format |
| 13224 | Invalid TwiML at webhook URL | Validate TwiML response from your server |
| 13225 | TwiML URL returned non-200 status | Fix your webhook endpoint |
CANNOT
- Cannot use a private TwiML URL — Must be publicly accessible. Use ngrok for local development only; deploy to a cloud provider for production.
- Cannot exceed ~4,096 characters in inline
twimlparameter — Use a TwiML URL for longer responses - Cannot call unverified numbers on trial accounts — Upgrade to paid or verify recipient numbers first
- AMD accuracy is ~85-90% — Expect some false positives/negatives. Tune
machineDetectionSpeechThreshold(default 2400ms) based on your results. - AMD adds latency —
Enablemode returns results faster but may misclassify short greetings.DetectMessageEndis more accurate but adds seconds before your app can act. - Cannot use AMD with SIP Trunking — AMD is only available on calls made via the Calls API
Next Steps
- TwiML verb reference (Say, Gather, Dial, Record, Conference, Pay):
twilio-voice-twiml - AI voice agents with real-time speech/LLM:
twilio-voice-conversation-relay - Improve answer rates (Branded Calling, STIR/SHAKEN):
twilio-numbers-senders
Version History
- 08dc189 Current 2026-07-05 19:10
