Voice AI glossary.
Plain-word definitions.
The terms you'll meet when you put AI voice agents on the phone in India, from barge-in and warm transfers to DND, 1600-series numbers and the DPDP Act.
0–9
- 140-series numbers140-series numbers are Indian phone numbers starting with 140, set aside by TRAI for regulated promotional calls, such as offers and sales calls. Since TRAI's February 2025 amendment, telemarketing can't come from ordinary 10-digit numbers. Under TRAI's 2026 amendment, 140 numbers must not be flagged as spam to the people receiving them.
- 1600-series numbers1600-series numbers are Indian phone numbers starting with 1600, set aside by TRAI for service and transactional calls, such as payment reminders and updates on an existing account. Banks, financial services firms and insurers have been directed to use them for these calls. Under TRAI's 2026 amendment, 1600 numbers must not be flagged as spam to recipients.
- 1601-series numbers1601-series numbers are Indian phone numbers starting with 1601, used for service and transactional calls alongside the 1600 series. In a first phase in August 2026, TRAI moved service and transactional calls from utilities, courier and logistics companies onto 1601 numbers. Under TRAI's 2026 amendment, 1601 numbers must not be flagged as spam to recipients.
A
- A2P callAn A2P (application-to-person) call is a voice call that an application, software or automated platform starts, with no person dialling it. TRAI's amendment of 18 September 2026 names autodialled calls, robo-calls and pre-recorded or artificial voices, so an AI voice agent's outbound calls are A2P calls and must be declared to the telecom operator in advance.
- AI voice agentAn AI voice agent is software built to handle a phone call from start to finish. It hears what the caller says, works out what they want, answers in a natural-sounding voice and then does the job the call was for, such as booking a visit, logging a promise to pay or passing the caller to your team.
- Auto dialerAn auto dialer is software that dials phone numbers from a list automatically, so nobody has to key them in. Basic auto dialers connect answered calls to a waiting telecaller or play a recording. AI-based dialers hand each answered call to an AI voice agent that holds the conversation itself.
C
- Call dispositionA call disposition is the label that records how a call ended, such as booked, callback requested, not interested or wrong number. Dispositions turn each conversation into a clear outcome that a team can count, report on and act on, for example by retrying, following up or removing a contact.
- Code-switching (Hinglish)Code-switching is moving back and forth between languages in a single conversation, often inside a single sentence. Hinglish, the everyday mix of Hindi and English, is the most familiar example in India: "Kal ka slot available hai kya, ya next week book karna padega?" Voice agents need to understand it and reply in kind.
- Cold transferA cold transfer, also called a blind transfer, sends a caller to another person, team or number without first briefing whoever picks up. The call is simply put through. It's quick to set up, but the caller usually has to explain their reason for calling all over again.
- Concurrent callsConcurrent calls are the number of phone calls a system can run at the same moment. For an AI voice agent, each concurrent call works like one phone line: with two, two conversations happen side by side, and the next call has to wait for a line to free up.
- Consent manager (DPDP)A consent manager is a service registered with India's Data Protection Board through which people can give, review and withdraw consent to businesses under the DPDP Act, 2023. Consent managers can register from about 13 November 2026. A business calling customers with AI doesn't need one, but should be ready to act on a withdrawal that arrives through one.
- Conversational AIConversational AI is the technology behind software that understands what people say or type and answers in everyday language. It brings together speech recognition for voice, a language model that works out meaning and the next step, and a way to reply, either as text in a chat or as a spoken voice on a call.
D
- Data fiduciaryA data fiduciary is whoever settles why personal data gets processed, and by what means, under India's DPDP Act, 2023 (section 2(i)). In an AI calling campaign, it's the business running the calls: it picks who gets called, why, what the agent asks and what's kept. The platform placing the calls for it is its data processor.
- DLT (distributed ledger technology) registrationDLT (distributed ledger technology) registration is how a business that sends commercial calls or messages in India records itself as a sender, and records its customers' consent, on the telecom operators' shared platform. Under TRAI's amendment of 18 September 2026, older consent counts only if it was taken in a verifiable way and is registered there.
- DND and the NCPRDND (Do Not Disturb) is the everyday name for the National Customer Preference Register (NCPR), TRAI's register of people's choices about commercial calls and messages. A person can block all commercial communication or only certain categories. A promotional call can reach a registered number only if the person's preferences allow it or they have given registered consent.
- DPDP ActThe DPDP Act is the Digital Personal Data Protection Act, 2023, India's law on how organisations collect, use, keep and delete personal data held in digital form. On an AI call that includes the phone number, the person's voice, the recording and the transcript. Most of its duties for businesses apply from 13 May 2027.
- DTMF (keypad input)DTMF, short for dual-tone multi-frequency, is the signal a phone sends when someone presses a key on its keypad. Each key produces its own pair of tones, so the phone system at the other end can tell which key was pressed. IVR menus and voice agents use it to read choices and numbers.
S
- Sentiment analysis (calls)Sentiment analysis is the automatic reading of the mood in a conversation, usually as positive, neutral or negative. On phone calls it looks at what the caller says, and sometimes how they say it, to show which calls went well, which went badly and where a person should step in.
- Speech recognition (ASR)Speech recognition, also called automatic speech recognition or ASR, is technology that turns spoken words into written text. On a phone call it converts the caller's voice into a transcript as they speak, so software such as an AI voice agent can understand the request and respond.
- Speed to leadSpeed to lead is how long a business takes to call a new lead after the enquiry comes in, whether from a website form, an ad or a missed call. A shorter gap means the person is more likely to remember the enquiry, pick up and talk.
T
- TCCCPR (TRAI's commercial communication rules)TCCCPR stands for the Telecom Commercial Communications Customer Preference Regulations, 2018: TRAI's rules for commercial calls and SMS in India. They cover DND preferences, consent on the DLT platform, the 140, 1600 and 1601 number series, complaints and spam. A Third Amendment introduced on 18 September 2026 brought AI and automated calls in as A2P calls.
- Text-to-speech (TTS)Text-to-speech, or TTS, is technology that turns written text into spoken audio. In an AI voice agent, the language model writes each reply as text and TTS speaks it in a chosen voice, with the pace, stress and pauses that make it sound natural to the caller.
V
- Voice botA voice bot is software that talks with people over the phone or another voice channel. Older voice bots follow fixed scripts and recognise a short list of phrases. Newer ones use speech recognition and language models to hold open conversations, and are usually called AI voice agents.
- Voicemail detectionVoicemail detection, also known as answering machine detection, is how an outbound calling system works out whether a call was picked up by a person or by a machine, such as a voicemail greeting or a network announcement. The agent then talks to the person, or deals with the machine as it has been set up to.
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