What is IVR?

A call opens with a greeting, either a recorded file or text read out by a synthetic voice. Numbered options follow: press 1 for sales, 2 for support, 3 for opening hours.

The caller answers on the keypad or by voice, and the system checks the input against the menu. A match sends the call to a team, a person, a queue, voicemail or another menu. Without a match, the options are read again.

The menu itself is a flow. Each step is a prompt, a wait for input and a set of branches that depend on the answer. Opening hours, out of hours and public holidays can each get their own route. By day the call reaches the team; at night the same number plays a message and may offer voicemail.

Each key on a phone sends a tone signal known as DTMF (dual-tone multi-frequency). ITU-T Recommendation Q.23 sets out the format. A key press plays two frequencies at once, one from a low group of four and one from a high group of four. Q.23 defines sixteen signals: the ten digits, star, hash and four keys marked A to D.

On internet calls, key presses travel as separate events rather than as sound. IETF RFC 4733 explains why: low-rate voice codecs cannot be relied on to reproduce the tones well enough for automatic recognition. Sent as an event, a key press arrives whatever the audio quality.

With speech input, the caller says a word instead of pressing a key. A classic IVR recognises only words and phrases defined in advance, and it does not follow open conversation. The W3C VoiceXML standard calls that list a grammar: the things a caller may say to take an action or give information.

A word outside the grammar is not recognised, and the options are read again. Silence runs out a timeout, and the menu restarts or the call takes a default route. VoiceXML treats the two cases as separate events, each with its own message.

The first problem is a question with no option. A menu covers the few most common reasons for calling. A caller asking about price, availability or an order has no obvious key to press. The caller guesses, lands with the wrong team or hangs up.

The second is time. Options are read one by one, so the caller listens until the right one comes up. Sub-menus stretch the wait: a three-level menu means three lists before the right team answers.

The third is the record. A keypad menu captures only the key that was pressed. What a caller wanted before giving up is written down nowhere, so the questions the menu misses stay invisible.

The last is upkeep. A new service or new opening hours means a new prompt and a rearranged flow. When that work waits, the menu reads out information that is no longer true.

An IVR asks the caller to choose; an AI voice assistant listens to the question. The caller explains in their own words, the speech becomes text, and the answer comes from the sources the business supplied.

The two do different jobs. A keypad menu exists to send the call to the right place. An AI voice assistant answers common questions itself: opening hours, the address, the service list and appointment requests. Where its sources have no answer, it makes nothing up and passes the call to a person with a written summary.

Cloud phone platforms already put the two side by side. Some let a menu step hand the caller to a bot that understands speech. Others extend the routing menu with AI agents that guide callers in conversation, without a fixed menu.

IVR works well where calls split into a few clear reasons. In a company with several departments, one key separates sales, support and accounts. Account and order numbers are also taken on the keypad.

An AI voice assistant fits where questions vary and the answers already sit with the business. In a salon, clinic, hotel or field service team, callers tend to ask about hours, the address, a price range or a free slot. Those answers do not fit a menu, but the business already holds them.

The two can also run together. The menu's first step splits calls by team, and one option leads to the assistant. Or the assistant answers every call, and only the topics on its handover list go to a team. ALTAI Digital agrees that list with the client during the build.