A call center dialer is software that works through a list of numbers and places the calls, so people (or AI voice bots) do not dial by hand. The types differ in how many calls they place for each available agent: manual and preview dialers place one when an agent asks, predictive dialers place extra calls on a forecast, and an AI dialer takes the conversation itself.
Last reviewed by the VoiceOI team
A dialer is the software that dials a call center's outbound lists. "Auto dialer" is the umbrella term, and the types you will see named are manual, preview, progressive, power and predictive, plus the newer AI dialer.
What separates them is pacing: how many calls the system places for each available agent. Predictive dialers place extra calls on a forecast, which is why they can reach a person when no agent is free. That is an abandoned call, and in the US it is limited (see the 3% rule below).
Vendors do not agree on what power and progressive dialing mean. Genesys, Five9, Regal, Dialpad, Mitel and ReadyMode each define them differently, so read a vendor's own definition before comparing two products. The table of definitions below quotes each one.
An AI dialer is a different kind of tool: the call is placed and handled by an AI voice bot, so there is no agent queue to pace around. VoiceOI is an AI dialer for outbound calls. It is not a predictive, power or progressive dialer.
Six ways a call center decides when to place the next call, from the most manual to the most automated.
| Dialer type | How it dials | Who talks to the person who answers | Abandoned-call risk | Fits best |
|---|---|---|---|---|
| Manual (click-to-dial) | The agent clicks to dial each number, usually from an on-screen list. | A human agent | None from pacing: nothing dials until an agent clicks. | Short lists and calls that need preparation. |
| Preview | Shows the agent the contact record first. The agent reviews it, then chooses to call or skip. | A human agent | Very low: the agent decides when each call is placed. | High-value or research-heavy leads. |
| Progressive | Places the next call when an agent is available. Vendors differ on how many numbers it dials per agent (see the definitions table). | A human agent | Lower than predictive, but not zero: Genesys says the risk "is not eliminated entirely". | Teams that want steady pacing without forecasting. |
| Power | Places calls when an agent is ready, often more than one per agent at a ratio the manager sets. Definitions vary by vendor. | A human agent | Moderate: extra calls per agent can reach a person before an agent is free. | Teams that want more calls per hour and can manage the abandonment rate. |
| Predictive | Uses an algorithm to predict when agents will be free and dials ahead of them. | A human agent | Highest: the FCC notes a person can answer and hear "dead air" because no agent is free. | Large teams on big lists, where idle agent time is the main cost. |
| AI voice bot dialer (VoiceOI) | Each bot places one call at a time from a lead list, or works VICIdial campaigns as a remote agent. Capacity is the number of bots. | The AI voice bot, then a human closer on a live transfer for people who qualify. | No agent queue to pace. Transfers still need a closer free, and consent rules for AI voices apply. | First-contact and qualification calls at volume. |
The abandoned-call column describes pacing risk in general terms, based on the definitions quoted below. It is not a measured rate for any product.
A dialer is the software that places a call center's outbound calls from a loaded list of contacts. Wikipedia's entry describes an auto dialer as a system that makes outgoing calls from a call centre based on a loaded list of contacts (Wikipedia: Auto dialer). The types below are different answers to one question: when should the next call go out?
Without a dialer, agents type or click every number and spend time on rings, busy signals and voicemail. A dialer removes that work and adds the controls a campaign needs: lead lists, calling hours, retries, call outcomes (dispositions) and recordings.
"Outbound dialer" just means a dialer used for outbound campaigns, as opposed to the queues that distribute inbound calls. Suites such as VICIdial® cover both. If you run VICIdial, see our VICIdial AI integration guide for how bots join its campaigns.
Preview dialing shows the agent a contact's record before any call is placed. Genesysdescribes preview as presenting contact information to the agent before dialing, after which "the agent reviews the customer record before deciding whether to call or skip to the next record." Five9says its preview dialers "allow sales reps to review customer contact records before dialing."
Because the agent chooses when each call goes out, preview is the slowest of the automated modes and the one where nobody is kept waiting for an agent. It suits calls where context matters: high-value leads, business prospects, accounts with history and callbacks.
Progressive dialing ties the pace to agent availability instead of to a forecast. Genesys: "The system automatically dials one contact for each available agent," and while the risk of abandonment is lower than with faster modes, "it is not eliminated entirely." Wikipedia describes a progressive dialer as one that "does not make further outbound calls where no agent would be available to handle the call when the callee answers."
Other vendors define it differently. Mitel's progressive dialing presents the contact to the agent and gives "a specific amount of time" to review it before the dialer places the call, which is closer to a timed preview. Regalsays a progressive dialer places "a preconfigured number of calls (e.g., 2 calls per agent)" for each available agent, and Five9 describes a "variable calls-to-agent ratio."
What the definitions share: the dialer does not simply work down the list at full speed. How many calls go out for each available agent, and whether the agent previews first, depends on the product.
Power dialing is where definitions diverge most. Five9describes power dialers that "continuously dial at a fixed number based on your desired calls-to-agent ratio." Genesysdescribes power mode as placing calls "to ensure that at least one live person answers" when an agent is ready, and slowing down when it reaches the configured abandonment threshold. Dialpadsays a power dialer ("sometimes called a progressive dialer") "automatically dials the next number on a list only when an agent is ready."
So "power dialer" can mean one call per free agent, a fixed ratio of several calls per agent, or something close to a predictive dialer without the forecasting. When you compare vendors, ask for the ratio and the abandonment controls, not the label.
The FCC defined it in 2003: "A predictive dialer is an automated dialing system that uses a complex set of algorithms to automatically dial consumers' telephone numbers in a manner that 'predicts' the time when a consumer will answer the phone and a telemarketer will be available to take the call." The same footnote adds that in some instances "a consumer answers the phone only to hear 'dead air' because no telemarketer is free to take the call" (FCC 03-153, footnote 31).
Vendors describe the same idea in their own terms. Five9says predictive dialers "calculate the number of calls to dial based on the average connect rate and historical agent statistics," and Genesysnotes that "the larger the agent pool, the more accurate the predictions can be."
Predictive pacing fits large teams working big lists, where idle agent time costs more than the occasional abandoned call, and where someone owns the abandonment rate. The next two sections cover how the definitions differ and what the US rule requires.
Quoted from each page as read on October 1, 2026. Vendors can change their wording, so check the page before relying on a definition.
| Source | Progressive dialing | Power dialing |
|---|---|---|
| Genesys Cloud | "The system automatically dials one contact for each available agent." | "When an agent is ready, the system places calls to ensure that at least one live person answers"; it slows down at the configured abandonment threshold. |
| Five9 | "Variable calls-to-agent ratio determining how many calls the system needs to place as reps become available" on its dialer system page, but "automatically dials one customer per available agent" on its outbound contact center page. | "Continuously dial at a fixed number based on your desired calls-to-agent ratio." |
| Regal | "A preconfigured number of calls (e.g., 2 calls per agent) are placed on behalf of each available agent." | "Agents are automatically connected to the call as it starts dialing." |
| Dialpad | Not defined separately: it says a power dialer is "sometimes called a progressive dialer." | "Automatically dials the next number on a list only when an agent is ready." |
| Mitel | Presents the contact to the agent, who is "given a specific amount of time" to review it before the dialer places the call. | Not covered on the page read. |
| ReadyMode | "Dials multiple numbers at a time but waits until an agent is available." | "Dials a preconfigured number or numbers at a time for each available agent." |
| Wikipedia | Does not make "further outbound calls where no agent would be available to handle the call when the callee answers." | "Agents do not become party to the call until the called party has picked up"; the system dials several contacts at once. |
Six of these sources define power dialing, in at least four different ways, and Five9 describes progressive dialing two ways on two of its own pages. That is why the label alone tells you very little about how a product paces calls.
VICIdial describes dial methods by setting name, not by the vendor labels above, so which label fits depends on whose definition you use.
| VICIdial dial method | What it does |
|---|---|
| MANUAL | Agents click to dial each number (the dial level is locked at 0). A manual preview option shows the lead before dialing. |
| RATIO | Dials a set number of lines for each active agent. |
| ADAPT_HARD_LIMIT, ADAPT_TAPERED, ADAPT_AVERAGE | Adaptive methods: the system adjusts the dial level automatically, up to the campaign's drop percentage limit. This is VICIdial's predictive pacing. |
From VICIdial's campaign help text and its documentation, read October 1, 2026. The setting list also includes INBOUND_MAN, and newer versions may add more. Check the help text in your own system.
Under the FTC's Telemarketing Sales Rule, a telemarketing call is "abandoned" if a person answers and the telemarketer does not connect the call to a sales representative within two seconds of the person's completed greeting (16 CFR 310.4(b)(1)(iv)).
The safe harbor in 310.4(b)(4) has four conditions: (1) technology that ensures no more than 3 percent of all calls answered by a person are abandoned, measured over the duration of a single calling campaign if it runs under 30 days, or separately over each successive 30-day period; (2) letting each unanswered call ring at least 15 seconds or four rings; (3) promptly playing a recorded message with the seller's name and telephone number when no sales representative is available within two seconds; and (4) keeping records that show compliance.
The FCC has a parallel rule at 47 CFR 64.1200(a)(7): no more than three percent of telemarketing calls answered live by a person, measured over 30 days for a single campaign, with a prerecorded identification and opt-out message and an automated opt-out mechanism when no live representative is available within two seconds.
Two cautions. First, carriers apply their own, different "abandoned" definitions and limits to calls that end before they are answered; see the SIP trunk guide. Second, the rule speaks of a "sales representative," and the sources we read do not say how it applies to a call handled by an AI voice bot. Treat that as a question for your lawyer. This page is not legal advice.
In February 2024 the FCC confirmed that the TCPA's restrictions on "artificial or prerecorded voice" "encompass current AI technologies that generate human voices," so calls that use them "require the prior express consent of the called party" unless an emergency purpose or exemption applies (FCC 24-17, paragraph 2, adopted February 2, 2024 and released February 8, 2024). For telemarketing calls, the FCC's rules call for prior express written consent (47 CFR 64.1200(a)(2) and (a)(3)).
VoiceOI offers an optional AI-voice disclosure and do-not-call phrase handling, and the consent duty stays with you. See TCPA controls for AI voice bots, do-not-call controls and the compliance page for what the product does and does not provide. This is not legal advice.
An AI dialer replaces the agent on the call, not your carrier or your lead list. Each VoiceOI bot places one call at a time, qualifies the person with a script you build in the no-code builder, and live-transfers qualified leads to a human closer. Capacity is the number of bots you run, as long as your SIP carrier has enough channels for them. See the AI auto dialer page for the controls and pricing.
There are two ways to run it. Inside VICIdial, bots log in as remote agents, so your lists and campaign settings stay in VICIdial and each call outcome is written back as a disposition (VICIdial AI voice bot). On its own, the built-in dialer works a CSV lead list through any SIP carrier with scheduling, retries and timezone windows (campaign manager).
VoiceOI does not pace calls for human agents. If you run a predictive or power dialer for people today, keep it for that and add bots next to it. Qualified calls go to your closers through a live transfer, so keep closers free for them.
Five questions that narrow the choice faster than comparing feature lists.
Every quotation and legal statement above comes from one of these pages. Links to vendors we compete with are marked nofollow.
Short answers on dialer types, the abandoned-call rule and where AI voice bots fit.
A dialer is software that places a call center's outbound calls from a loaded list, so agents do not dial each number by hand. The types differ in pacing: manual, preview, progressive, power and predictive, plus AI dialers where a voice bot handles the call.
A predictive dialer uses an algorithm to forecast when agents will be free and dials ahead of them, so a person can answer when no agent is available. Vendors define power dialers differently: Five9 describes a fixed calls-to-agent ratio, while Dialpad describes dialing the next number only when an agent is ready. Ask a vendor for its ratio and its abandonment controls rather than relying on the label.
Not consistently. Dialpad says a power dialer is sometimes called a progressive dialer, while Five9, Genesys and Regal describe them as different modes with different ratios. The table of definitions on this page quotes each vendor.
A preview dialer shows the agent the contact record before any call is placed. In Genesys's words, the agent reviews the record before deciding whether to call or skip to the next record.
The FTC Telemarketing Sales Rule safe harbor allows no more than 3 percent of calls answered by a person to be abandoned, measured per campaign over its duration if under 30 days, or over each successive 30-day period. It also requires connecting a sales representative within two seconds of the greeting or playing a recorded message, letting calls ring at least 15 seconds or four rings, and keeping records. The FCC has a parallel rule. This is not legal advice.
No. VoiceOI places calls with AI voice bots, one concurrent call per bot, and live-transfers qualified leads to your closers. It does not pace calls for human reps. If you pace reps today, keep VICIdial or your current dialer for that and add bots as extra remote agents.
In 2024 the FCC confirmed that AI technologies that generate human voices count as an artificial or prerecorded voice under the TCPA, so such calls need the called party's prior express consent, and the FCC's rules call for prior express written consent for telemarketing calls. VoiceOI offers an optional AI-voice disclosure and do-not-call phrase handling, but the consent duty stays with you. This is not legal advice.
VICIdial's dial method setting includes MANUAL, RATIO, the adaptive methods ADAPT_HARD_LIMIT, ADAPT_TAPERED and ADAPT_AVERAGE, and INBOUND_MAN, according to VICIdial's documentation. Newer versions may add methods, so check the help text in your own system.