OBD (Outbound Dialing or Outbound Broadcasting) is an automated system that places calls to a list of contacts and plays a pre-recorded or text-to-speech voice message without any live agent involvement. The call is entirely automated from start to finish — the system dials the number, plays the message when answered, optionally collects a DTMF key-press response, and logs the outcome. A predictive dialler, by contrast, is designed to connect answered calls to a pool of live human agents — it predicts when agents will be free, dials ahead of those predicted availability windows, and aims to have a live call ready the moment an agent finishes their previous conversation. The key distinction is human agent involvement: OBD is fully automated and can broadcast millions of calls per day without any agent resource; predictive diallers are designed to maximise agent talk time and always involve a human on the other end. OBD is the right choice for EMI reminders, appointment alerts, survey calls, delivery notifications and awareness broadcasts. Predictive diallers are the right choice for sales teams, collections teams and service departments where a live conversation is required to achieve the outcome.

OBD calls in India are classified as Unsolicited Commercial Communications (UCC) under TRAI's framework and are subject to strict regulations. The most important requirement is DND (Do Not Disturb) compliance: TRAI maintains a National Do Not Call (NDNC) registry of mobile and landline numbers whose subscribers have registered to block commercial calls. Calling a DND-registered number without prior explicit consent can result in a penalty of ₹500 to ₹1,500 per call under the TRAI Telecom Commercial Communications Customer Preference Regulations. DND scrubbing is the process of comparing your contact list against the NDNC registry and removing DND-registered numbers before a campaign runs. TRAI requires telemarketers to scrub lists every 7 days, as registry updates are ongoing. Additional regulations include: calls may only be placed between 9am and 9pm; the calling line identity (CLI) must be a TRAI-registered 10-digit telemarketer number starting with 140; and your organisation must be registered as a telemarketer on the DLT platform. All listed OBD providers perform automated DND scrubbing before every campaign run and provide a scrubbed-contact report as part of the campaign analytics.

DTMF (Dual-Tone Multi-Frequency) collection means your OBD message includes a menu prompt — "Press 1 to speak to our collections team, Press 2 to confirm payment by UPI, Press 3 to reschedule" — and the system captures the key the recipient presses after hearing it. The captured DTMF response can trigger several actions: transferring the answered call to a live agent or contact centre queue (Press 1 connects to your team); sending a webhook or API call to your CRM to update the contact record with their response; sending a follow-up SMS with a payment link if they pressed 2; scheduling a callback if they pressed 3; or aggregating responses in the campaign dashboard for real-time analysis. DTMF collection is what converts a passive OBD campaign (the contact hears a message and does or does not act later) into an interactive one (the contact responds in the moment, when their attention is focused on the call). In Indian lending and collections, DTMF-enabled OBD campaigns consistently generate 2–4× the agent connection rate of simple voice broadcast campaigns because the friction of taking an action is reduced to pressing a single key.

Personalised TTS (Text-to-Speech) OBD allows each call in a campaign to play a message customised to that specific recipient — speaking their name, their account number, their due amount, their appointment time or their order details. This is achieved by passing variable fields from your contact list to the OBD platform at campaign upload time (e.g., first_name, loan_id, amount_due, due_date), and the platform generates a unique TTS audio file for each contact by substituting these variables into the message template. The voice quality for personalised fields in Indian OBD varies significantly. Number amounts (₹12,480 spoken as "barah hazaar chaar sau aassi rupaye" in Hindi) are handled accurately by most providers with good Indian numeral TTS. Personal names are the most error-prone: names like "Prabhakaran", "Krishnaswamy" or "Veeraswamy" are commonly mispronounced by standard TTS engines, and the mispronunciation of a customer's name in a call is the single most effective way to cause them to disengage immediately. We test personalised TTS on a sample of 20 Indian names from each target language — including uncommon names — before listing any provider for personalised OBD campaigns.

Concurrency in OBD refers to the number of simultaneous live call channels the platform is placing at any given moment. To estimate required concurrency for a campaign, consider: your total contact list size, the time window in which you want to complete the campaign, the average call duration (typically 30–60 seconds for OBD including ring time and message), and your expected first-attempt answer rate (typically 55–65% in India). As an approximation, to dial 500,000 contacts in a 4-hour window with a 55% answer rate and 45-second average call duration, you need approximately 500,000 × 45s / (4 × 3600s) = ~1,562 channels — but accounting for unanswered numbers that still consume channel time while ringing, effective concurrency requirement is typically 2–3× higher, so approximately 3,000–5,000 simultaneous channels for this campaign. Most Indian OBD providers offer concurrency from 500 to 50,000 channels, with pricing tiers for different concurrency bands. We verify that the provider has actually sustained the claimed concurrency in documented production campaigns, not just laboratory tests, before listing.

OBD (Outbound Dialing or Outbound Broadcasting) is an automated system that places calls to a list of contacts and plays a pre-recorded or text-to-speech voice message without any live agent involvement. The call is entirely automated from start to finish — the system dials the number, plays the message when answered, optionally collects a DTMF key-press response, and logs the outcome. A predictive dialler, by contrast, is designed to connect answered calls to a pool of live human agents — it predicts when agents will be free, dials ahead of those predicted availability windows, and aims to have a live call ready the moment an agent finishes their previous conversation. The key distinction is human agent involvement: OBD is fully automated and can broadcast millions of calls per day without any agent resource; predictive diallers are designed to maximise agent talk time and always involve a human on the other end. OBD is the right choice for EMI reminders, appointment alerts, survey calls, delivery notifications and awareness broadcasts. Predictive diallers are the right choice for sales teams, collections teams and service departments where a live conversation is required to achieve the outcome.