Add a Vocal Bot to Your App

The way users interact with applications is fundamentally changing. The era of tap-and-type is evolving into a more natural, intuitive paradigm: the conversation. For developers, the mission is clear, it’s time to add a Vocal Bot to your app. This AI-driven feature, capable of listening, processing, and responding in real time, is no longer a futuristic novelty. It’s a strategic imperative for boosting engagement, improving accessibility, and delivering a truly hands-free user experience.

Leveraging a new generation of powerful SDKs, developers can now integrate voice capabilities with remarkable speed. However, after the initial success of launching an in-app assistant, many teams encounter a critical and often unforeseen limitation, a ceiling that consequently caps the feature’s ultimate business value and traps their intelligent creation in a digital silo.

The Anatomy of an In-App Vocal Bot

Before we explore this limitation, let’s deconstruct the technology. A modern Vocal Bot is powered by a seamless, low-latency pipeline that simulates a human-like conversation, all orchestrated by an SDK or API.

1. Audio Capture: The journey begins when the app, using its integrated SDK, captures the user’s speech via the device microphone.
2. Speech-to-Text (ASR): The raw audio stream is sent to an AI model that transcribes it into text in real time.
3. AI Language Model (LLM): The transcribed text is then fed to the “brain” of the operation, the app’s chatbot logic or an LLM backend which analyzes intent and formulates a response.
4. Text-to-Speech (TTS): The AI’s text reply is converted back into natural, lifelike audio by a TTS engine.
5. Audio Playback: The synthesized audio is streamed back to the app and played for the user, completing the conversational loop.

SDKs from providers like Sendbird, Kore.ai, and IBM Watson make this entire workflow accessible, enabling developers to build sophisticated in-app voice experiences.

The Hidden Limitation: The Problem with an App-Only Voice

You’ve successfully integrated a powerful SDK. Your app now has an intelligent Vocal Bot that can guide users, answer questions, and perform tasks. It gets rave reviews. Then, the business asks a crucial question: “This is fantastic, but can our customers call this bot for support when they aren’t in the app?”

Suddenly, you hit a wall. The very SDKs that are perfect for in-app communication are not designed to interface with the global telephone network. The Public Switched Telephone Network (PSTN) is a completely different ecosystem. Your sophisticated AI is effectively trapped inside your application.

A customer who needs urgent help, is driving, or simply prefers to call a support number will not be able to reach your bot. Furthermore, their natural instinct is to dial a phone number, not to find and open your app. Consequently, at that moment, your entire investment in voice AI becomes inaccessible, and the customer journey is broken.

FreJun: The API That Connects Your App to the World

This is the exact problem FreJun was engineered to solve. We are not another in-app voice SDK, but the specialized voice infrastructure platform that acts as the universal bridge, connecting the intelligent AI you’ve already built to the global telephone network.

We design FreJun to provide a simple, developer-first SDK and API that handle all the complexities of telephony. Furthermore, we manage the phone numbers, the SIP trunks, the media servers, and the low-latency audio streaming. Consequently, this allows you to take the exact same AI brain you created for your app and make it available over a standard phone number.

FreJun doesn’t replace your in-app tools; instead, it makes them infinitely more valuable by breaking them out of their silo and enabling a true omnichannel voice strategy. Consequently, this is how you create a Vocal Bot that serves all your users, everywhere.

Pro Tip: Design for Explicit User Triggers

To build trust and respect user privacy, always design your Vocal Bot with explicit triggers. Avoid “always-on” listening. Instead, use a clear tap-to-talk button or a well-defined wake word to initiate voice input. The FreJun AI SDK is designed with this principle in mind, ensuring users are always in control of the conversation.

In-App SDKs vs. FreJun’s Omnichannel Approach: A Comparison

Feature	In-App Only Vocal Bot SDKs	An Omnichannel Vocal Bot with FreJun
User Accessibility	Limited to users who have the app installed and open.	Universally accessible to anyone with a phone, plus all in-app channels.
Primary Use Cases	In-app help, feature guidance, voice commands.	24/7 customer support lines, virtual receptionists, automated sales calls, enterprise service.
Infrastructure Burden	Low. Managed by the in-app SDK’s backend.	Zero telephony infrastructure to build. FreJun manages the entire voice stack.
Business Impact	A modern UX feature that improves engagement for app users.	A strategic asset that reduces operational costs and serves all customer segments.
Developer Focus	Mobile app development and client-side SDK integration.	Backend development and creating a unified AI experience.

How to Add a True Vocal Bot to Your App in 5 Steps

This guide outlines the modern architecture for creating a voice AI that works both inside your app and over the phone.

Step 1: Build Your Centralized AI Core

On your backend server, architect the core conversational pipeline. This logic will be responsible for taking an input, orchestrating the calls to your chosen STT, LLM, and TTS APIs, and producing an output. This “brain” will serve all your channels.

Step 2: Integrate Your In-App Voice SDK

In your mobile or web app, integrate your chosen SDK (like Sendbird Voice SDK or VoxSDK) for the in-app experience. Configure it to stream the user’s microphone audio to your backend and to play the audio it receives in response.

Step 3: Integrate FreJun’s SDK for Telephony

This is the step that connects your app’s AI to the outside world.

1. Sign up for FreJun and provision a virtual phone number.
2. Use FreJun’s server-side SDK in your backend code to handle incoming WebSocket connections from our platform.
3. Configure your FreJun number’s webhook to point to your backend’s API endpoint.

Step 4: Route All Audio to Your AI Core

Your backend is now ready to receive audio from two sources. When a request comes in, you simply pipe the audio stream, whether it’s from the mobile app or from a FreJun-powered phone call, into your centralized AI logic from Step 1.

Step 5: Return the Synthesized Response to the Right Channel

Once your AI core generates the synthesized audio response, you stream it back to the source it came from. If it was an in-app request, it goes back to the mobile app’s SDK. If it was a phone call, it goes back to the FreJun API, which plays it to the caller.

With this architecture, you have successfully built a single, powerful Vocal Bot that serves all your users, on any channel.

Key Takeaway

To successfully add a Vocal Bot to your app, a two-part strategy is required. First, use a dedicated in-app SDK to create a seamless client-side experience. Second, use a specialized infrastructure API like FreJun’s to connect your bot’s AI to the telephone network. This hybrid approach is the key to creating a truly omnichannel, enterprise-grade voice solution without the immense cost and complexity of building your own telecom stack.

Best Practices for a Flawless Voice Experience

• Optimize for Latency: Aim for a round-trip response time of under one second to make the conversation feel natural. This requires optimizing your entire pipeline, from the mobile client to the backend APIs.
• Support Fallback to Text: Always provide a way for users to see the transcribed speech and correct errors, or to switch to a text-based chat. This is critical for accessibility and for handling noisy environments.
• Test for Diversity: Test your bot’s performance across different devices, operating systems, accents, and levels of background noise to ensure a consistent and reliable experience for all users.
• Secure Everything: Never hardcode API keys in your mobile app. Persist authentication tokens securely on the device. Ensure all data streams are encrypted to protect user privacy.

Final Thoughts: From a Cool Feature to a Business-Critical Asset

The future of mobile interaction is conversational. Adding a Vocal Bot to your app is a critical step into that future. It makes your application more accessible, more engaging, and more human. But the true value of that voice is measured by its reach.

An assistant that is trapped inside your app is a helpful feature. An assistant that can also manage your company’s phone line is a revolutionary business tool. It can scale your support, automate sales processes, and deliver a level of service that was previously unimaginable.

Don’t let your investment in AI be limited by the confines of a single channel. The strategic path forward is to combine the best in-app SDKs with a robust infrastructure partner. FreJun provides the simple, powerful, and reliable API to bridge that gap, allowing you to focus on what you do best: building a brilliant app with a voice that can be heard everywhere.

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Further Reading – Build a Voice-Based Conversational AI With an SDK

Frequently Asked Questions (FAQ)