What is an AI phone assistant? Technology, limits, law, cost

Why this matters right now

Small businesses have a reputation for being hard to reach by phone: in a representative survey in Germany, 60 % of respondents said small companies in particular are always or often hard to reach (YouGov/Enreach, April 2023, 2,099 respondents). At the same time, 36 % of German companies cannot fill open positions, at least in part (DIHK skilled-labour report 2025/26, ~22,000 companies). A business that cannot hire someone for the phone loses calls — and the jobs that came with them.

How an AI phone assistant works

Behind every conversation runs a chain of three steps, several times a minute:

1. Speech recognition (STT): what is said is continuously turned into text.
2. Language model (LLM): an AI model works out what the caller wants, decides the next step (answer a question, take a callback number, check a slot, put the call through) and phrases the reply.
3. Speech synthesis (TTS): the reply is turned back into a natural-sounding voice.

That chain has to complete fast enough that no unnatural pauses creep in. Response speed is one of the largest quality differences between providers — and the reason a good assistant picks up before the caller hangs up.

Worth being clear about: an AI phone assistant is not a phone menu ("press 1 for sales"). It follows no fixed tree. It responds to what the caller actually says, including when they change the subject mid-sentence.

What one can do today

• Answer around the clock, and in parallel when several people call at once
• Take the request in a structured way: name, callback number (good systems read a dictated one back digit by digit), what it is about, how urgent it is
• Answer questions — serious systems answer only from the knowledge base they were given, and invent nothing
• Book appointments directly into genuinely free slots in the calendar (Google Calendar or Outlook, for example)
• Recognise emergencies and put them through to a number you have set
• Speak several languages, some switching mid-call
• Summarise: after every call there is a transcript and a summary, by email, SMS or in the dashboard

What it cannot do — the honest list

• It does not replace an expert conversation. Complex advice belongs to a person — the assistant captures the request and organises the callback.
• It is only as good as its knowledge base. Without maintained content it can take messages and little else.
• Some callers do not want an AI. A share of them hang up once they realise — how large that share is depends heavily on the industry and on the greeting. More on that in "Do callers notice they are talking to an AI?".

How the caller reaches the assistant

The standalone providers in this category work on the same principle: the assistant gets its own phone number, and the business forwards calls to it — immediately, when the line is busy, or after a few rings. Your own number stays exactly as it is, and nothing has to be rebuilt on your phone system. An app that "hooks into your existing number" without forwarding does not technically exist (the article "Does an AI phone assistant need an app?" explains why).

What the law requires

Two things are settled (general information, not legal advice):

• AI disclosure: since 2 August 2026, Article 50(1) of the EU AI Act requires that people be told they are interacting with an AI at the latest at the start of the interaction, unless that is obvious anyway. The duty falls on the provider of the AI system; on the phone that means the assistant says so in the greeting.
• GDPR: the provider processes call data on the business's behalf, which means a data processing agreement, clear retention periods, and transparency about which sub-processors are involved. One important difference between providers: some record calls as audio, others store only transcripts.

Origin matters to buyers here: 93 % of companies in Germany would prefer a German provider for AI solutions (Bitkom, September 2025, 604 companies with 20 or more employees).

What does it cost?

The range runs from free or single-digit entry offers with clear limits (as of November 2026) up to several hundred euros for industry solutions with software integration. A common price point is around €99 a month. The full calculation is in "What does an AI phone assistant cost?".

Who is it worth it for?

Briefly: any business that loses calls because nobody can pick up — trades on site, practices with a busy front desk, property managers taking fault reports, self-employed people in a client meeting. It is not worth it if someone is always on reception anyway and the call volume is small.