Build a Voicemail Generator with ElevenLabs API

A developer published a walkthrough for building a voicemail generator that uses the ElevenLabs text-to-speech API to synthesize personalized greetings and clone custom voices from short audio samples. The tutorial wraps the TTS and voice-cloning endpoints in a Flask service exposing a single /voicemail endpoint that accepts a caller name, message, and optional voice ID and returns generated audio.

When you’re building a contact‑center or a smart‑home system, the last thing you want is an empty voicemail box. A little voice‑AI can turn a static “no answer” message into a personalized, dynamic greeting that feels like a real person. In this post we’ll walk through how to create a Voicemail Generator using the ElevenLabs Text‑to‑Speech TTS API. We’ll cover everything from authentication to generating a voice‑cloned message, then bundle it into a simple Flask app that can be called via webhook or a REST endpoint. The result? A lightweight service that lets you generate a voicemail audio file on the fly, using the same high‑quality voices you can clone with ElevenLabs. Let’s dive in. | Item | Description | |---|---| | Python 3.8+ | For the example code | | pip | To install dependencies | | ElevenLabs API key | Sign up at https://try.elevenlabs.io/kr07zfuqn1bp https://try.elevenlabs.io/kr07zfuqn1bp | | Basic knowledge of Flask | We’ll expose a simple HTTP endpoint | Tip : If you’re new to ElevenLabs, the link above gives you a free trial with credit to test the API. ElevenLabs offers a powerful, low‑latency TTS endpoint that supports voice cloning, speaker embeddings, and a large library of natural‑sounding voices. The API is REST‑based, so you can call it from any language. Store it in an environment variable for security: export ELEVENLABS API KEY="sk your key here" curl -X POST "https://api.elevenlabs.io/v1/text-to-speech/eleven monolingual v1" \ -H "xi-api-key: $ELEVENLABS API KEY" \ -H "Content-Type: application/json" \ -d '{"text":"Hello, this is a test."}' You should receive an audio stream in the response body. Great You’re ready to embed this into an app. ElevenLabs lets you clone a voice by providing a short audio clip. For a voicemail system, you might want to use a company‑wide voice e.g., a receptionist or a custom voice that matches your brand. python import requests import os API KEY = os.getenv "ELEVENLABS API KEY" BASE URL = "https://api.elevenlabs.io/v1" def clone voice audio file path, voice name : """Clone a new voice from an audio sample.""" headers = { "xi-api-key": API KEY, "Content-Type": "application/json", } data = { "voice name": voice name, "audio url": None, We'll upload the file directly } Upload the audio file first with open audio file path, "rb" as f: files = {"file": f} upload resp = requests.post f"{BASE URL}/audio/upload", files=files, headers={"xi-api-key": API KEY} upload resp.raise for status audio url = upload resp.json "url" Create the voice data "audio url" = audio url resp = requests.post f"{BASE URL}/voices", json=data, headers=headers resp.raise for status return resp.json "voice id" Remember : The cloned voice is stored in your ElevenLabs account and can be reused across calls. You’ll get a voice id that you’ll pass to the TTS endpoint. We’ll create a Flask service with a single endpoint: /voicemail . It accepts JSON containing a caller name , a message , and an optional voice id . The service will: bytes stream. python from flask import Flask, request, send file, jsonify import requests import os import io app = Flask name ELEVENLABS API KEY = os.getenv "ELEVENLABS API KEY" BASE URL = "https://api.elevenlabs.io/v1" def synthesize text text, voice id : headers = { "xi-api-key": ELEVENLABS API KEY, "Content-Type": "application/json", } payload = { "text": text, "voice id": voice id, "model id": "eleven monolingual v1", } resp = requests.post f"{BASE URL}/text-to-speech/{voice id}", json=payload, headers=headers, stream=True resp.raise for status return resp.content @app.route "/voicemail", methods= "POST" def voicemail : data = request.json caller = data.get "caller name", "Someone" message = data.get "message", "I couldn't answer your call." voice id = data.get "voice id" if not voice id: Fallback to a default voice voice id = "EXkTlv5x2jJ5fK8V2i9F" Replace with your own default voice ID full text = f"Hi, this is {caller}. {message}" audio bytes = synthesize text full text, voice id return send file io.BytesIO audio bytes , mimetype="audio/mpeg", as attachment=True, download name="voicemail.mp3", if name == " main ": app.run debug=True POST /voicemail { "caller name": "Alice", "message": "Sorry I missed your call, please leave a message after the tone.", "voice id": "EXkTlv5x2jJ5fK8V2i9F" } voicemail.mp3 . The synthesize text helper streams the audio directly from ElevenLabs, so you’re not holding large buffers in memory. Now that we have the core logic, let’s test the service locally. Start the server python app.py In another terminal, call the endpoint: curl -X POST "http://localhost:5000/voicemail" \ -H "Content-Type: application/json" \ -d '{"caller name":"Bob","message":"Please leave a message after the beep."}' \ -o voicemail.mp3 Open voicemail.mp3 with your favorite player – you should hear a natural‑sounding greeting. If you want to use a cloned voice, pass the voice id you obtained earlier. /voicemail endpoint into a Twilio webhook so that when a call is missed, Twilio automatically plays the generated audio. ElevenLabs’ TTS API gives developers the ability to create high‑quality, personalized voicemails with minimal effort. By cloning a voice and exposing a simple REST endpoint, you can turn any missed call into a brand‑consistent, engaging experience. If you’re ready to give your voicemail system a voice upgrade, grab a free trial and start experimenting today. Sign up here: https://try.elevenlabs.io/kr07zfuqn1bp https://try.elevenlabs.io/kr07zfuqn1bp and let ElevenLabs bring your voicemails to life