What Is Voice AI? Evolution, Technology, Added Value

"Press 1 for sales. Press 2 for support. Press 3 for..."

Everyone knows this voice on the phone. And hardly anyone likes hearing it. Anyone who calls and ends up in a touch-tone menu is frustrated before the conversation has even begun.

Voice AI is the answer to this frustration. It is the evolution of traditional voice dialogue systems powered by generative AI. Where earlier systems guided callers through rigid tree structures, modern Voice AI understands natural language, answers questions from a knowledge base, and executes processes autonomously. By 2027, an estimated 50% of all service requests will be resolved by AI, up from 30% in 2025 (Salesforce State of Service, September 2025).

This article explains what Voice AI is, how it works, and why it is a no-brainer for companies today.

1. From touch-tone to natural language

The history of voice technology goes back further than many think. As early as 1911, a toy dog named Rex jumped out of his doghouse when his name was called. That was the first recorded example of automatic speech recognition. From the 1970s onwards, touch-tone IVR systems shaped customer service over the phone. Speech recognition, if used at all, was limited to keywords and number sequences. The systems were clunky and frustrated callers.

The next phase began in the early 1990s. At the Department of Pattern Recognition in Erlangen, researchers developed Evar and FränKi, the world's first natural language dialogue systems. Evar was an information system for Deutsche Bahn. FränKi knew which cinema was screening the latest James Bond film. In 2003, this team gave rise to Sympalog Voice Solutions GmbH, which continues to develop voice dialogue systems to this day.

The breakthrough in user adoption did not come from customer service, but from everyday life. Siri, Alexa, and Google Assistant made talking to a computer second nature. In late 2022, OpenAI launched ChatGPT. By mid-2025, voice experiments had evolved into widely adopted products: Amazon released Alexa+, Apple introduced Siri with goal-oriented conversation flow, and Google launched Gemini Live for real-time voice conversations.

Three terms are important to distinguish:

IVR system

An IVR system (Interactive Voice Response) is a voice menu that guides callers through a fixed dialogue tree via keypad input or basic voice commands. Touch-tone IVRs are the oldest form and are still widely used today.

Voice dialogue system

A voice dialogue system (also called a voicebot or voice portal) is software that enables people to communicate with a computer via spoken language. Modern systems rely on AI and understand full sentences, ask clarifying questions, and respond flexibly to the caller's request.

Voice AI

Voice AI is the current generation of voice dialogue systems that utilizes generative AI and Large Language Models to conduct natural conversations, generate answers from a knowledge base, and execute processes autonomously. The use of LLMs and the ability to operate without predefined dialogue trees are the defining characteristics.

2. How Voice AI works: The technology behind the phone

A modern Voice AI system consists of four technology building blocks that work together seamlessly.

Speech-to-Text (STT): Converting speech into text. The first step is speech recognition. Modern speech recognition systems like Whisper belong to the category of Automatic Speech Recognition (ASR) models. They are extremely fault-tolerant, multilingual, and recognize speech even with widely varying audio quality, dialects, or background noise. Speech recognition converts voice into text. However, it does not yet understand the meaning behind the statements.

Natural Language Understanding (NLU): Recognizing intent. The second step is understanding. Put simply, NLP (Natural Language Processing) stands for searching for words or phrases in a question. But as soon as questions become more complex, NLU is essential. The AI looks at the entire question, examining the subject, object, pronouns, and intent. This allows the system to properly classify inquiries such as "I want to exchange the item, but I've already unpacked it."

Enterprise Search and knowledge base: Finding the answer. The third step is knowledge retrieval. The system searches a knowledge base for the appropriate answer: product database, FAQ system, CMS, CRM, DMS, or a combination thereof. This is where the quality of any Voice AI is determined. A Voice AI is only as good as the knowledge base it accesses.

Text-to-Speech (TTS): Speaking the answer. The fourth step is voice output. Modern TTS voices sound so natural today that they are fully viable for production use. Cloud-based TTS solutions have become affordable despite their high quality.

Latency as a critical factor. On the phone, any pause is fatal. Modern real-time voice systems achieve an end-to-end latency of under 300 milliseconds. The Red Phone, a London-based provider of natural language routing, operates with under 600 ms latency and 99.9% uptime in over 30 languages.

The crucial difference compared to the past: Previously, dialogues and grammars had to be maintained manually. Today, small amounts of training data or zero-shot classification with LLMs are sufficient. Large Language Models like GPT, Claude, or Llama dynamically guide dialogues based on conversational context, without predefined dialogue trees.

3. Why Voice AI is a no-brainer today

Three developments make Voice AI unconditionally attractive for companies today.

The technology is mature. Speech recognition achieves 90% accuracy. Text-to-Speech voices sound natural. Latency is under 300 milliseconds. 89% of service professionals say Conversational AI increases self-service resolution rates (Salesforce State of Service, September 2025). The technology is proven in production use worldwide.

Costs are low. A voice dialogue system does not need thousands of daily calls to be cost-effective. Newcall, an AI phone assistant for tourist information centers in the DACH region, is available starting at €650 per month (new-call.de, 2026). Fonio, the volume player in the German market with 9,500+ customers, can be set up in minutes (OMR, 2026). What used to be a major IT project is now a SaaS subscription.

The benefits are real. Voice AI delivers 24/7 availability, multilinguality, scalability during call spikes, and insights from conversation data. Newcall answers guest inquiries in over 25 languages. The Red Phone replaces rigid IVR menus with natural language routing in over 30 languages. 70% of travelers would skip the reception desk when checking into a hotel. Among Gen Z, that figure is 82% (Mews Survey, June 2025). Guests want information immediately, in their language, and without waiting times.

If you are still running touch-tone IVR today, you are losing callers. The question is not if, but when and how you introduce Voice AI.

4. Where Voice AI is already working today

Voice AI can be deployed across industries. Wherever standardized processes and connected systems exist, it can handle requests independently.

Industry	Concrete Inquiries	Added Value
Tourism & Transportation	Opening hours, event information, reservations, travel details	24/7 multilingual guest support, relief for tourist information centers during peak season
Financial Services	Account balance, transaction history, transfers, branch info, PIN management	Self-service for standard inquiries, voice authentication
Energy & Utilities	Meter readings, outage reports, plan changes, billing questions	Buffer for call spikes caused by service disruptions
E-commerce & Retail	Order status, returns, Click & Collect, product availability	Assisting checkout completion over the phone
Public Administration & Citizen Hotlines	Appointment scheduling, public information, form requests	Around-the-clock availability without expanding staff
Healthcare	Appointment booking, prescription requests, follow-up care info	Relief for practice staff

A concrete example from tourism: A guest inquiry at 11 pm asking for the nearest pharmacy. No tourist information center is staffed at that hour. A Voice AI connected to destination data answers the question immediately in the guest's language. Newcall does exactly that, with a go-live within one week (new-call.de, 2026).

Voice AI bridges the gap because it meets callers right where they already are: on the phone.

5. Voice AI needs a central knowledge base

Voice AI on the phone is only as good as the knowledge base it accesses. Even the best language model cannot deliver useful answers if company data is incomplete, outdated, or unstructured.

branchly does not provide its own Voice AI. branchly is the central knowledge base and dashboard connecting Voice AI solutions like Pendura, The Red Phone, Fonio, or Newcall with your website AI. The voice technology comes from the partner; the database and insights come from branchly. All four providers are direct branchly partners and integrate natively into the branchly platform.

The principle is simple: You set up your content once in branchly as a knowledge base. Website copy, FAQs, product data, PDFs, event calendars, external databases. This knowledge base then applies to every module: Chat on the website, hybrid Search, Advisor, Navigator, Forms, and the voice agent on the phone.

What changes when all interfaces come from a single source:

No conflicting information. Phone and website draw from the same knowledge base. A customer receives the exact same answer over the phone as in chat.
No duplicate maintenance effort. You maintain one knowledge base, not two. Every update takes effect across all channels immediately.
One compliance standard. GDPR, EU AI Act, and WCAG/BFSG are resolved once, not per channel. One platform, one DPA, one audit trail. Microsoft Azure EU hosting for LLMs, OVH Cloud for user data. Nothing leaves the EU.
One dashboard. All voice and web insights in a single interface. Call topics become FAQ candidates. Frequent questions turn into content. Data turns into actionable recommendations.

branchly has processed over 40 million AI-powered sessions and supports 101 languages natively. That is the difference between "buying Voice AI" and "implementing Voice AI strategically."

To learn how to implement Voice AI properly in five steps, read our article Implementing Voice AI the Right Way in 5 Steps. To discover why isolated Voice AI is not enough, check out Why Isolated Voice AI Is Not Enough.

Summary

Voice AI is the evolution of traditional voice dialogue systems powered by generative AI. This evolution moved from 1970s touch-tone IVR systems through the first natural language dialogue systems of the 1990s to modern systems that understand natural language, generate answers from a knowledge base, and execute processes autonomously.

The technology is mature, costs are low, and the benefits are real: 24/7 availability, multilinguality, scalability during call spikes, and insights from conversation data.

The key takeaway: Voice AI on the phone is only as good as the knowledge base it accesses. branchly does not offer its own Voice AI, but serves as the central knowledge base connecting Voice AI partners with your website AI. One database for six modules. One platform, one dashboard, one compliance standard.

If you are still running touch-tone IVR today, you are losing callers. If you introduce Voice AI strategically, you gain data that drives your marketing forward.