Voice AI has its own words.

ASR (automatic speech recognition) and STT (speech to text) are two names for the same job: turning spoken audio into written words. Researchers tend to say ASR, and API products tend to say STT.

Character error rate, or CER, scores a speech recogniser letter by letter instead of word by word. A small spelling slip costs a little, where word error rate would count the whole word as wrong.

Code-switching is moving between two languages inside one conversation, often inside one sentence. Hinglish, the mix of Hindi and English you hear on so many Indian business calls, is the everyday example.

SSML, the Speech Synthesis Markup Language, is a W3C standard for adding instructions to text before a voice reads it. Tags can ask for a pause, stress a word, or say how a number or date should be read.

Text normalisation turns written shorthand into the words a voice should say. Digits, dates, currency amounts, abbreviations and codes all need it before text-to-speech can read them out.

Voice activity detection, or VAD, is the part of a voice system that tells speech apart from silence and background noise, many times a second. Everything else in the call waits on its answer.

Word error rate, or WER, measures how often a speech recogniser gets words wrong. It counts the words it swapped, missed or added, and divides by the number of words that were really said.

BYO telephony, or bring your own carrier (BYOC), means the voice AI platform makes and takes calls on your phone numbers and your telecom account. You keep the numbers, the carrier contract and the carrier's bill, and the platform supplies the agent.

Caller ID, or CLI (calling line identification), is the number a person sees when your call rings. A number pool spreads your outbound calls across several numbers, so no single one calls too many people too fast.

DND, short for Do Not Disturb, is the preference a mobile user in India registers with their telecom operator to block promotional calls and messages. It began as the National Customer Preference Register (NCPR); under TRAI's current rules the preferences sit on the operators' shared DLT platform.

μ-law and A-law are the two standard ways phone networks squeeze voice into one byte per sample, defined in ITU-T G.711. A phone call carries 8,000 of those samples every second.

A SIP trunk is a phone line delivered over the internet: a connection from a carrier that lets software place and receive ordinary phone calls. One trunk can carry many calls at once.

TCCCPR is TRAI's rulebook for commercial calls and messages in India. An A2P (application-to-person) call is one that software places without a person dialling it, and TRAI's 2026 amendment gives it rules of its own.

A billing block, or pulse, is the unit a call's length is rounded up to before it's charged. With 10-second blocks, a call is billed in small slices instead of whole minutes.

Concurrency is how many calls, or speech streams, a system runs at the same moment. It's the number of lines open at once, and with call length it sets how many calls you can finish in an hour.