What is voice broadcasting?
Voice broadcasting, known in India as OBD (outbound dialling), is an automated calling campaign. A dialler works through a list of phone numbers, places the calls over the PSTN and plays a pre-recorded or text-to-speech (TTS) message to everyone who answers. Listeners can respond on the keypad: press 1 to confirm, 2 to speak to an agent, 9 to stop such calls. The platform records, for every number, whether the call connected, how long it was heard and which keys were pressed.
The economics are a funnel. A share of calls is never answered, a share of answered calls hangs up within seconds, and only some listeners stay to the end and press a key. Charges are usually for connected calls by duration, often in fixed pulses set by the provider, so a short, front-loaded message called at the right hour matters more than list size. Common uses are payment and EMI reminders, cash-on-delivery confirmation, appointment reminders, public announcements and promotions; voice OTPs use the same technology one call at a time.
In India voice broadcasting is commercial communication under TCCCPR. Promotional calls must come from 140-series numbers, which moved onto DLT on 1 October 2024, and are scrubbed against the DND registry (NCPR) and recorded consent; since August 2024, unregistered senders placing promotional calls over SIP or PRI lines face disconnection and blacklisting. Banks, NBFCs and other regulated financial entities moved their service and transactional calls to 1600-series numbers under a TRAI direction with deadlines in early 2026. A voice broadcast differs from an IVR, which answers inbound callers with menus, and from a WhatsApp template broadcast, which reaches opted-in contacts in chat.
Key takeaways
- Voice broadcasting (OBD) automatically calls a list and plays a recorded or text-to-speech message to everyone who answers.
- Listeners respond with keypresses (DTMF), for example 1 to confirm, 2 for an agent or 9 to opt out.
- Cost follows connected minutes, but results follow the funnel: answered, listened, pressed a key, acted.
- In India promotional calls must come from DLT-registered 140-series numbers and respect DND preferences and consent.
- Unlike an IVR, which answers incoming calls, a voice broadcast is one-to-many outbound calling.
Where does a voice broadcast lose its listeners?
57% drop-off · 28,500 calls (illustrative) lost
26.5% drop-off · 5,700 calls (illustrative) lost
37.3% drop-off · 5,900 calls (illustrative) lost
78.8% drop-off · 7,800 calls (illustrative) lost(biggest leak)
40.5% drop-off · 850 calls (illustrative) lost
Stage 6 of 6
Paid within 48 hours
1,250 calls (illustrative)
59.5% of the previous stage made it here (40.5% drop-off, 850 calls (illustrative) lost). That is 2.5% of the top.
The outcome to optimise, not dials or answers.
- Top to bottom
- 2.5%
- Biggest leak
- Heard the full message → Pressed 1 for a payment link (78.8%)
Stage 6 of 6: Paid within 48 hours, 1,250 calls (illustrative). 59.5% of the previous stage made it here (40.5% drop-off, 850 calls (illustrative) lost). That is 2.5% of the top. The outcome to optimise, not dials or answers.
Why does voice broadcasting matter?
Voice reaches people that text does not: customers who cannot read a long message, who rarely open SMS, or who respond better to a spoken reminder in their own language. A well-run campaign can confirm thousands of COD orders or EMI dates in an afternoon, with a keypress as a clear signal. Run badly, from the wrong number series, to people who blocked calls, with a 40-second preamble, it produces complaints, blacklisted numbers and a bill for calls nobody listened to.
How does voice broadcasting work?
Prepare the list and the permissions
Use numbers you have a relationship with, keep consent records for promotional calls, and let DLT scrubbing remove anyone whose DND preference blocks the category.
Record or synthesise a short message
Aim for 20 to 40 seconds with the key fact in the first five: who is calling and why. Record per language, or use TTS for messages with variables such as amounts and dates.
Set up the dialler
Choose the right caller ID (140-series for promotions, the 1600 series for regulated financial service calls), the calling window, the number of simultaneous channels and retries for busy or unanswered numbers.
Calls go out and play
Each answered call plays the message. Keypresses are captured as DTMF and can transfer the caller to an agent, schedule a callback or trigger an SMS or WhatsApp follow-up.
Read the funnel and adjust
Report answer rate, listen-through, keypress rate and cost per response by hour, language and list, then change the script, the timing or the audience, not just the volume.
Example: EMI reminders for a Nagpur lender
A Nagpur two-wheeler finance company calls 50,000 customers three days before their EMI date from its 1600-series number, in Marathi and Hindi. About 43% answer, and the illustrative funnel above shows where the rest drop: many hang up before the amount is read out. Moving the due date and amount into the first six seconds lifts listen-through, and customers who press 1 receive a UPI payment link on WhatsApp seconds later. The team now judges the campaign on payments received after a keypress, not on calls dialled.
Key facts at a glance
Voice broadcasting: key facts and limits
- Also called
- OBD (outbound dialling), voice blast
- Message length
- Typically 20 to 40 seconds
- Response capture
- DTMF keypresses (some platforms add speech)
- Billing
- Connected calls by duration, in provider-set pulses
- India, promotional caller ID
- 140-series numbers on DLT (since 1 Oct 2024)
- India, BFSI service calls
- 1600-series numbers (TRAI direction, deadlines early 2026)
- Core metrics
- Answer rate, listen-through, keypress rate, cost per response
Common wrong turns
Common mistakes with voice broadcasting
Calling from the wrong numbers
Promotional calls from ordinary 10-digit numbers or unregistered SIP and PRI lines can get every connection disconnected and the sender blacklisted. Use a registered provider and the designated number series.
A long introduction
Most hang-ups happen in the first seconds. Say who you are and why you are calling at once, and keep greetings and music out of the opening.
Ignoring preferences and consent
Calling people who blocked promotional calls without recorded consent drives complaints under TCCCPR. Let DLT scrubbing run, and keep your own opt-out list.
No opt-out key
Without a way to stop the calls, annoyed listeners complain instead. Offer a keypress to opt out in every promotional message and honour it across campaigns.
Counting dials instead of outcomes
A campaign that dials 50,000 numbers says nothing about results. Track keypresses, transfers and conversions, and compare cost per response with SMS or WhatsApp.
Good practice
Best practices for voice broadcasting
- Test two scripts on a small slice of the list before calling everyone.
- Retry unanswered numbers at a different time of day rather than immediately.
- Use TTS for personalised amounts and dates, recorded voice for brand messages.
- Hand callers who press for help to a cloud telephony queue staffed during calling hours.
- Print a missed call service number in the message so listeners who hang up early can still ask for a callback.
- For two-way conversations rather than announcements, the WhatsApp Business Calling API lets customers call you from the chat they already use.