Caller ID and pacing

The Numbers tab of a Dialer campaign sets the caller ID each contact sees and how fast the campaign dials. You choose the numbers the campaign calls from, called its number pool, and how they rotate, then cap the campaign’s concurrent calls and calls per second (CPS). Open the tab from a draft campaign, or click Edit on a launched campaign’s page.

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Choose how numbers rotate

Under Phone number setup, pick one option:

• Local presence dialing: “Match local area codes to improve pickup rates.” This is the default. Each contact is called from a number assigned to its own area.
• Round robin phone numbers: “Initiate call from your numbers pool.” Each new contact gets the next number in the pool, so calls spread evenly across every number.

In both modes, a contact keeps the caller ID it got first for every later call and text, as long as that number stays in the pool. The contact sees one number from your campaign, and a callback to that number reaches the campaign. See Build a sequence for how callbacks are handled. The choice locks at launch. For example, a solar installer calls 6,000 leads across Texas with local presence. Dallas leads see a 214 number, Houston leads see a 713 number, and leads in smaller towns see the installer’s Default phone number.

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How local presence picks a caller ID

The Numbers by area code card lists the regions where your contacts are, ranked by contact count, with a United States or Canada tab for each country that has contacts. A region is a group of area codes that serve the same place, such as all the overlay codes of one city. Eleven metro regions, such as Bay Area, CA and New York Metro, NY, combine several neighboring areas. A number you assign to a region can call every contact in all of its area codes. When a contact is due, Retell picks its caller ID in this order:

1. The caller ID the contact already has from this campaign, if that number is still in the pool.
2. A number assigned to the contact’s region. The contact’s country and area code must match the region exactly. When a region has several numbers, they take turns.
3. A number in the Default phone number row: “Used to call contacts when you haven’t added a number for their area code.” Contacts outside the US and Canada also use this row.
4. If none of these exist, the contact fails with “No number available to call from” and isn’t called.

Retell doesn’t fall back to a nearby area code at dial time. To cover a region with a number from a different area code, click Set up on the region, then Use other area code. Each region row shows how many numbers it has and a suggestion, such as “Suggest 3 numbers.” Retell suggests one number per 50 contacts in the region, and at least one. Click Set up (or Edit, once the region has numbers) to pick numbers you own in that region or plan new ones. Auto-fill sets up every region at once. It selects each number you own in a region that has contacts, then fills in purchase quantities so each region reaches its suggestion. Review the quantities on the United States and Canada tabs, then click Save.

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Add numbers you own

Any number in your workspace can join the pool, including numbers you connected through custom telephony.

• Round robin: click Add numbers, select numbers under Reusing numbers you own, and click Save.
• Local presence: click Set up on a region. The list shows the numbers you own in that region’s area codes.

Campaign calls use the agents in your sequence, not the number’s own outbound agent. A number can be in more than one campaign at a time. A toll-free number from Retell can call US numbers only. A contact outside the US that gets a toll-free caller ID fails with “Destination not allowed”. Under local presence, every toll-free number you buy for the campaign joins the Default phone number row, including toll-free numbers planned on the Canada tab. If you call contacts in Canada, don’t buy toll-free numbers for the campaign, and keep toll-free numbers you own out of a round robin pool and out of the Default phone number row.

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Buy new numbers

While the campaign is a draft, you can plan new numbers in the Buy new numbers section of the Add numbers or Auto-fill dialog. Local numbers cost $2 per month and toll-free numbers cost $5 per month (as of October 2026).

• A region’s dialog offers that region’s area codes.
• The round robin dialog and the Default phone number row offer Normal numbers, which can have any US area code, and Toll free.
• Auto-fill offers area codes, normal numbers, and toll-free numbers in both the US and Canada.

Saving the dialog saves the plan but buys nothing. Planned numbers show “Bought at launch” until Retell buys them, in one of two ways:

• Now: on the Overview tab, click Purchase on the Phone numbers card. Retell “buys the numbers now and adds them to this campaign.”
• At launch: when you click Launch Now or Schedule Launch, Retell buys the remaining planned numbers. For a scheduled campaign, the numbers are bought and billed from that moment, not from the start time.

Both ask you to choose a provider: Twilio (the default) or Telnyx. Telnyx sells US local numbers only. If you choose Telnyx, Purchase skips the Canadian and toll-free numbers, and launch is blocked until you switch to Twilio or remove them. When you buy US numbers at launch, the confirm dialog has a second step that asks whether to verify them first. Verify first, launch in 7 days is selected by default, and the button reads Schedule and verify. This moves the start to at least 7 days from now, so Launch Now does not dial until then. A start time you picked later than 7 days out stays. To keep your start time, select Skip for now. Verified numbers cost $10 per month each. If you click Purchase on the Overview tab instead, the same choice appears as Purchase and verify. It does not change when the campaign starts. A campaign can use at most 500 numbers in total (as of October 2026). Keep the numbers you own plus the new numbers you plan to buy at or under 500. The dashboard checks the two counts separately, so a pool over 500 can fail after the purchase, once the numbers are already bought and billed. Numbers you buy stay in your workspace and in the campaign’s pool, even if the launch fails after the purchase. They’re billed monthly until you delete them on the Phone Numbers page. See Purchase phone number for how number billing works. After launch, you can’t plan purchases in the campaign. Buy numbers on the Phone Numbers page, then add them as numbers you own.

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SMS requirements

If your sequence has an SMS node, two rules apply to the pool:

• Every number must be SMS-enabled. That means a Retell Twilio number with an approved A2P campaign, or your own Twilio number set up for SMS. See Enable SMS.
• The plan can’t include new numbers. Newly bought numbers can’t send SMS, so Purchase is disabled. Remove planned numbers on the Numbers tab.

Launch is blocked until both rules hold, with a message such as “The sequence sends SMS, but 2 numbers can’t.” After launch, Retell rejects a pool change that adds a number without SMS.

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Spam and reputation

Carriers can label a number that places many calls as “Spam Likely”, and a recycled number can arrive already flagged. Retell doesn’t replace flagged numbers in a campaign automatically. To keep pickup rates up:

• Use enough numbers. More numbers means fewer calls from each one. Follow the suggestion of one number per 50 contacts.
• Check new numbers. After Retell buys them, turn on Daily spam check for them on the Phone Numbers page. It checks carrier spam flags every 24 hours, for US numbers only, and costs $2 per month per number (as of October 2026).
• Register your numbers. Apply for a verified phone number and branded call, both for US numbers.
• Swap out flagged numbers. Remove a flagged number from the pool and add a clean one. The change reaches the campaign within about 15 minutes, and contacts that had the flagged number then get a new caller ID.

See the Spam Likely overview for how to check a number’s status.

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Set the dialing rate

The Dialing capacity section caps how many calls the campaign runs at once and how fast it starts them. Both are caps, not reservations: they limit this campaign, but they don’t hold capacity for it.

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Campaign concurrency limit

The campaign concurrency limit is the most calls this campaign runs at the same time. In the dashboard, the default is half your workspace concurrency limit, rounded down, but never more than your workspace limit minus the inbound reserve. A campaign created through the API without a dialing capacity has no campaign limit.

• The lower limit wins. The campaign runs at most its own limit, and never more than the workspace’s free outbound capacity.
• No burst, no inbound reserve. Campaign calls never use concurrency burst or the reserved inbound concurrency.
• Shared capacity. All campaigns, your other outbound calls, and web calls share the same outbound capacity. Several campaigns can each set the full amount, and the first call ready takes the next free slot. Hover over Other in the “Total limit · Inbound reserve · Other” line to see the other campaigns’ limits.
• Calls wait at capacity. When no slot is free, the next call waits until one opens. Waiting doesn’t use one of the contact’s attempts.

If your workspace has no inbound reserve, a notice reads “No concurrency is reserved for inbound calls.” If this campaign’s limit also takes all outbound capacity, it reads “No concurrency is left for inbound calls.” Raising your workspace limit doesn’t raise the campaign’s limit. Update it here too. Adjust concurrency opens the Adjust concurrency limit dialog. It changes your workspace, not just this campaign: set Concurrent calls and Inbound reserve. Each concurrent call above your included limit costs $8.00 per month (as of October 2026). You’re charged immediately when you increase the limit, and a decrease doesn’t change charges for the current billing cycle. In the Dialer, this button is available to Admins only. Developers can change the concurrent calls on Settings > Limits, but not the inbound reserve.

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Calls per second (CPS)

CPS caps how many calls the campaign starts each second, separately for each telephony provider: Twilio, Telnyx, and Custom Telephony. SMS steps don’t count toward the concurrency or CPS limits. A call counts against the provider of the number it’s placed from. The card shows the sum, such as “3 CPS capacity”. By default, the campaign can use your full workspace CPS for each provider. A workspace has 1 CPS per provider unless it’s been raised. All campaigns share the workspace CPS. To cap the campaign lower, click Adjust CPS limit and set a value for each provider, between 1 and your workspace limit. This buys nothing. To raise workspace CPS, adjust it on Settings > Limits. After you confirm, the campaign keeps these values even if you buy more workspace CPS later. CPS calculator opens the same calculator as the Limits page.

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Live estimates

The Live estimates panel estimates how fast the campaign can reach your contacts. Edit the inputs to test scenarios: The panel returns:

• Capacity: calls per hour. It’s the lower of what CPS allows and what concurrency allows, since only answered calls hold a line for the average duration.
• Time: how long one call to each of the Total contacts takes.
• Costs: an estimate for the answered first calls: contacts × answer rate × average duration × the starting agent’s price per minute, plus $0.01 per minute when the pool has Retell Twilio or Telnyx numbers. It shows a dash unless the sequence starts with a phone call node that has an agent.

Estimates leave out ringing time, retries, and later sequence steps. “Changing these inputs does not change campaign limits.”

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What you can change after launch

On the campaign page, click Edit and open Numbers. For a stopped or completed campaign, the button reads Details and every tab is read-only. Until then, you can:

• Add or remove numbers you own. You can’t remove the last number.
• Change the campaign concurrency limit and CPS.

You can’t switch between local presence and round robin, or plan new purchases. Changes to numbers, concurrency, and CPS save when you click Done or switch tabs. Save in the numbers dialog only stages the change, and Back to campaign discards it. Concurrency and CPS changes apply from the next call. Number changes reach the campaign within about 15 minutes. A call already in progress keeps its caller ID. Once the campaign is stopped or completed, the Numbers tab is read-only. Its numbers stay in your workspace and keep their monthly fee until you delete them.

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FAQ

Related: Dialer overview, Choose contacts, Build a sequence, and Understand concurrency & limits.