Predictive, Progressive, Preview or SIM Dialer? Types Explained
By Pushpa Godara · Chief Executive Officer, Wappblaster
Short answer: For a small Indian sales team calling its own leads, the best type is a SIM-based mobile auto dialer like RMDialer. It dials one number after another from the phone's own SIM, so customers see a real mobile number and there is no per-minute bill. Predictive dialers suit call centres with 25 or more agents.
Key takeaways
- A predictive dialer rings more numbers than there are free agents, so some customers answer to silence and hang up.
- A progressive or power dialer rings one number for each free agent right after the last call, so no call is abandoned.
- A preview dialer shows the lead record first and waits for the agent to start the call, which is slow but well prepared.
- One SIM can make only one call at a time, so a single phone reaches about 150 to 250 dials a day.
Shopping for a dialer means wading through four words that every vendor uses and almost none explain: predictive, progressive, preview, power. They describe genuinely different machines with different costs and different failure modes. Here is the honest map.
Predictive dialer: the call-centre machine
A predictive dialer calls more numbers than there are agents free, using statistics to predict how many calls will connect and how long conversations last. When a human answers, the system grabs a free agent and connects them mid-hello.
- Built for: 25+ agent call centres grinding big lists, where a few seconds saved per call compounds into real money.
- The cost: cloud telephony pricing (per user plus per minute), setup, and a statistical gamble: when the maths guesses wrong, the customer says “hello?” into silence and hangs up. Those abandoned calls are the classic predictive-dialer signature, they annoy people, and they are exactly the behaviour spam-flagging systems punish.
- In India: regulators and caller-ID apps make aggressive predictive dialing on virtual numbers increasingly self-defeating: connect rates fall as the number’s reputation does.
Progressive and power dialers: one call per agent
A progressive dialer (power dialer is mostly marketing for the same idea) calls one number per free agent, automatically, as soon as the previous call ends. No over-dialing, no silent calls: the agent hears every ring.
- Built for: outbound teams that want rhythm without the call-centre gamble.
- The trade: slightly fewer dials per hour than predictive, in exchange for zero abandoned calls and a cleaner number reputation.
Preview dialer: read first, then dial
A preview dialer shows the agent the lead’s record and waits for them to trigger the call. Highest preparation, lowest speed.
- Built for: high-value, low-volume calling: renewals, big-ticket follow-ups, collections conversations where reading the history first changes the outcome.
SIM-based mobile auto dialer: the fourth type vendors skip
The three types above traditionally assume cloud telephony: virtual numbers, per-minute billing, agents at desks. The fourth type runs the same progressive logic on an ordinary Android phone, through its own SIM: pick a list, press start, the phone dials one lead after another, and the after-call sheet captures the outcome in two taps.
What changes economically and practically:
- The customer sees a normal mobile number, which in India is the single biggest connect-rate lever there is: SIM calls get answered, virtual numbers get screened.
- Calls cost your operator’s normal rate, often effectively zero on unlimited plans: no per-minute cloud bill.
- Preview behaviour comes free: the lead’s status and last remark are on the call screen during the ring, so every call is a prepared call without the preview dialer’s slowness.
- The ceiling is real: one SIM makes one call at a time, so a single phone tops out around 150-250 dials a day. Scale comes from more phones and reps, not from over-dialing, and each rep’s numbers report centrally.
The four types in one table
| Type | Calls per free agent | Runs on | Abandoned calls | Fits | India note |
|---|---|---|---|---|---|
| Predictive | more numbers dialled than agents, by statistics | cloud platform, virtual numbers | yes, by design | call centres of 25+ agents | regulated silence and abandonment; per-minute billing |
| Progressive / power | one, dialled the moment the last ends | cloud or phone | none | most sales teams | the right default shape |
| Preview | one, after the agent reads the record and triggers it | cloud or phone | none | high-value, low-volume calling | slowest, most prepared |
| SIM-based mobile | one, from the SIM in the phone | an Android phone | none | Indian SMB teams calling their own leads | real number shown, no telephony bill, calls need no mobile data |
A SIM-based mobile auto dialer is a progressive dialer by pace and a phone by architecture, which is why the three types vendors describe never quite fit an Android sales team until the fourth row is added. RMDialer, which we make, is that fourth row.
Which type fits you
- 25+ seat call centre, huge cold lists, recording mandatory → predictive or progressive on cloud telephony, eyes open about number reputation.
- 2-20 person Indian sales team, own leads, WhatsApp follow-ups → SIM-based mobile auto dialer; this is RMDialer’s home ground, at ₹159/user/month with the CRM built into the dialer itself.
- Few but precious calls → preview-style calling, which a SIM dialer does naturally by showing the record before and during every call.
The vendor test: ask what happens to your connect rate in month three. Predictive-on-virtual-numbers usually cannot answer that honestly. A clean SIM number, dialed at human rhythm to people who expect the call, can.
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