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Yotel exposes three outbound dial modes. They are selected per-campaign via the dial_mode field on POST /v1/campaigns. Industry vendors use many overlapping names for the same behaviours (power dial, auto dial, ratio dialer); this page maps Yotel’s canonical names to the terms you may already know.

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Preview

In preview mode, the agent sees the lead’s details (name, previous notes, last disposition) and manually clicks Dial to place the call. The dialer does not originate the leg until the agent confirms. When to use it. High-value outbound — B2B sales, enterprise renewals, collections escalations — where the agent needs context before speaking. Also the right choice for low-volume lists where agent idle time is not the bottleneck. Industry aliases. Preview dial. Sometimes called “manual dial” when there is no lead-record preview step, but Yotel always surfaces the lead card.

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Progressive

In progressive mode, the dialer places exactly one call per available agent. The moment an agent becomes idle, the next lead in the list is dialed; as soon as the lead answers, the call is connected to that agent. Ratio is always 1:1 — the dialer never over-dials. When to use it. Mid-volume outbound where you want to keep agents busy but cannot tolerate any abandoned calls. Good default for most Indian BPO campaigns because it plays nicely with TRAI DND requirements and avoids the regulatory risk of abandoned calls. Industry aliases. Power dial. Auto dial. 1:1 dialer. “Power dialer” and “auto dialer” are used interchangeably with progressive across most US/EU vendors — Yotel’s term is progressive.

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Predictive

In predictive mode, the dialer over-dials using an Erlang-B-based ratio-aware algorithm. It places more calls than there are free agents, betting that some will go to voicemail, ring out, or be busy. Answered calls are routed to the next available agent via the ACD queue. When to use it. High-volume outbound where agent utilisation dominates the economics — telesales, lead qualification, survey, collections-at-scale. You need a floor of roughly 20+ agents for the statistics to work reliably. Industry aliases. Ratio dialer. Over-dialer. Predictive dialer. All refer to the same basic shape: dial ratio > 1.0.

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How Yotel protects abandon rate

TRAI and most global regulators cap “abandoned” calls (answered by the lead but no agent available within a short window). Yotel enforces a hard 3% abandon-rate cap — this is non-negotiable and built into the predictive engine itself:
  • The dial ratio is continuously recomputed from rolling answer-rate, AHT, and agent-available stats.
  • Each campaign has predictive_target_abandon (default 0.025 — 2.5%) which is the soft target; the engine dials below this.
  • If the 15-minute rolling abandon rate approaches 3%, the engine automatically throttles the ratio toward 1.0 (effectively becoming progressive) until the rate drops.
  • predictive_max_wait_s caps how long an answered lead waits for an agent before being released — preventing the worst UX failure mode.
You cannot disable the 3% cap via the API. It is a platform invariant.

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Voice broadcast pattern

A common question: “Is voice broadcast a fourth dial mode?” No. Voice broadcast is a flow-composition pattern layered on top of either progressive or predictive. The campaign still uses dial_mode: "progressive" (or "predictive"); what differs is the post-answer action. A voice-broadcast campaign sets:
  • post_answer_action: "run_flow"
  • The flow itself is a small 3-block IVR:
    • play_audio — the recorded broadcast message.
    • collect_digits — typically max_digits: 1, timeout_s: 5, waiting for the lead to press 1 to opt in.
    • connect_agent — routes confirmed opt-ins to the agent queue.
The dialer UI ships a “Use voice-broadcast template” button on the campaign-create page that pre-fills this flow shape. Because voice broadcast is just a flow, you can extend it freely: add a second prompt, branch on multiple digits, send the opt-out to a DNC-update webhook, etc. Everything other flows can do is available here.