Who Builds the Prospect List: The SDR Agency, You, or Both? (2026)

A good outsourced SDR agency builds the prospect list, with your input, from several sources, verifies senior contacts by hand, and hands the whole thing over to you when the engagement ends. An agency that only calls the list you supply is an appointment setter, not an SDR function, whatever the proposal says. Both are legitimate; you should know which you are buying, because the list decides more of the outcome than the callers do.

This guide covers the three list building models, what a well built Australian list contains, where the data comes from, who owns it, and the questions to ask before you sign.

TLDR

• Agency builds. The standard for outsourced SDR. You supply the ICP; they supply and verify the list.
• Client supplies. Common in appointment setting. Cheaper, and only as good as your data.
• Hybrid. You supply target accounts or a customer list; the agency maps contacts, enriches and verifies.
• Whatever the model, the list, the enrichment and the CRM records should be yours at exit. Write it down.

The three models

Model 1: the agency builds it

You provide an ICP: size, sector, geography, situation. The agency turns that into 1,500 to 3,000 named accounts, maps two contacts per account, sources phone and email, verifies senior contacts by hand, suppresses your existing customers and open opportunities, and tags segments for testing. This is what "outsourced SDR" should mean. It is skilled work and it takes most of the first two weeks of an engagement.

Model 2: you supply it

You hand over a list from your CRM, a database export or a purchased file, and the agency calls it. Fast to start and cheap. The risk is that most client supplied lists are stale, thin on phone numbers, heavy on wrong titles and include people you already sell to. Our companion guide on appointment setters vs SDRs covers when this model is the right one.

Model 3: hybrid

You supply the accounts (a target account list, a lookalike of your best customers, a conference attendee list) and the agency builds the contacts around them: mapping the buying committee, sourcing mobiles and direct dials, verifying, enriching. This is often the best structure for companies with strong account knowledge and weak contact data, which describes most mid market B2B firms.

What a well built Australian list contains

Six components. If a proposed list is missing two of them, it is a database export, not a list.

1. Named accounts fitting a situational ICP. Not just size and sector. Regulated, growing, recently funded, using a competitor, hiring for a role your product supports. Our ICP framework covers the situational layer.
2. Two contacts per account. The budget holder and the influencer or user. Called with different angles.
3. Verified mobile or direct dial for senior contacts. Australian mobile coverage in global databases is thin. This is the component most often faked.
4. ABN linkage. Records tied to an Australian Business Number can be deduplicated and verified. Records tied to a company name string cannot.
5. Suppressions. Existing customers, open opportunities, do not contact requests, recent losses.
6. Segment tags. So the weekly review can say "segment C is dead, segment A is working" rather than "the list is not great".

How a list gets built in two weeks

The agency build model, step by step, so you know what you are paying for in the first fortnight.

Days 1 to 2: ICP to criteria. The ICP document is translated into database filters and manual rules. Size band, sectors (by ANZSIC or by keyword where sectors are fuzzy), geography, technology signals, situational markers. The rules are written down so the list can be rebuilt the same way next quarter.

Days 3 to 5: account universe. Every company matching the firmographic criteria is pulled from an Australian native platform and a global platform, deduplicated on ABN where possible, and scored against the situational criteria. A universe of several thousand becomes 1,500 to 3,000 accounts, tiered.

Days 6 to 8: contact mapping. Two contacts per account: the budget holder and the influencer. Titles verified against LinkedIn Sales Navigator. Where the obvious title does not exist (many mid market firms have no Head of IT), the actual owner of the problem is identified from the org structure.

Days 9 to 11: phone and email sourcing. Mobiles and direct dials from the local platform first, global platform second, manual research third for tier one accounts. Emails from the global platform, verified.

Day 12: suppressions. Existing customers, open opportunities, do not contact requests, recent losses, competitors and partners removed. This step is skipped more often than any other and it is the one that causes the most embarrassment.

Days 13 to 14: sample review and load. A 50 account sample goes to the client for review. The list is loaded to the CRM and the dialler with segment tags. Calling begins on the test segment.

Translating an ICP into list criteria: a worked example

A hypothetical ICP for a company selling compliance software to financial advice firms, and how it becomes filters.

Every row is written down, so the list can be regenerated and so the client can see why any account is on it.

The suppression file checklist

Before the first call, remove or flag:

• Current customers, by ABN and by domain
• Open opportunities in the client's CRM
• Closed lost opportunities in the last six months (call them later, differently)
• Do not contact requests from any prior campaign
• Competitors and their subsidiaries
• Partners, resellers and referrers
• Employees of the client and their immediate family businesses where known
• Any number flagged as a consumer number on a Do Not Call Register wash

The client supplies the first three and the sixth; the agency handles the rest. Refresh the suppression file monthly.

Refresh cadence

Where Australian list data comes from

No single source is enough. A well built list in 2026 typically combines three.

An Australian native platform for phone data. Local providers with ABN verified records consistently outperform global platforms on Australian mobile hit rates (1). This is where the direct dials come from.

A global platform for breadth and email. Apollo, ZoomInfo or Cognism for company coverage and email addresses, accepting that phone fields will be emptier for Australian contacts.

LinkedIn Sales Navigator for the truth about who does what. The freshest title and company data anywhere, with no contact details. Used to validate the other two.

Some agencies run these through an orchestration layer such as Clay to enrich in sequence. Our ranking of B2B database providers for Australia compares the platforms, and our guide to data brokers vs managed services vs agencies covers the buy versus build decision.

Verification: why senior contacts get checked by hand

Industry estimates put B2B contact data decay around 3 percent a month (2). A list built in January has lost a material share of its accuracy by mid year. For a CFO or a Head of IT, a wrong number or a stale title on a cold call costs more than the two minutes it takes to check. Good agencies verify every senior contact before the first dial and re verify anyone not reached in 90 days.

Ownership: what should be yours

The account list with all enrichment.

The contact records including verified numbers.

The CRM records created during the engagement: every conversation, every note, every objection tag.

The messaging written for your campaign.

Get this in the contract. Some agencies build on their own platform and hand over a spreadsheet at exit, or nothing. Some pass through data provider licence terms that restrict transfer; ask them to confirm the data they supply can be handed to you. Our SDR agency contracts guide has the clause.

Who pays for the data

Three arrangements.

Included in the retainer. The agency carries its own subscriptions and the cost is inside the monthly fee. Most common and simplest.

Passed through. The agency bills data costs separately at cost or with a margin. Acceptable if itemised.

Client supplies subscriptions. You give the agency seats on your own database. Works if you already have good data tooling; otherwise it adds a procurement step to onboarding.

Whichever applies, it should be written down before the set up fee is paid.

When client supplied lists go wrong

Four failure modes we see on lists clients bring to us.

Stale. Built for a campaign eighteen months ago. A quarter of the titles are wrong.

No phone numbers. An email marketing export with 5 percent mobile coverage. Unusable for a phone first program without rebuilding.

Wrong titles. Marketing managers on a list meant for CFOs, because a database filter was set loosely.

Existing customers included. Nobody suppressed the current customer base. The first week of calling embarrasses everyone.

The fix is the same in every case: treat the client list as a set of target accounts and rebuild the contacts around it. Model 3.

Questions to ask before signing

1. Who builds the list, and from what sources?
2. How many accounts and contacts per account?
3. How are senior contacts verified, and how often re verified?
4. Can I see a sample of 50 accounts before launch?
5. Who owns the list, the enrichment and the CRM records at exit?
6. Are there licence terms on the data that restrict handover?
7. Who pays for data, and is it itemised?

How Nousu builds lists

Nousu Collective builds a named account list for every campaign from a combination of an Australian native platform, a global platform and Sales Navigator, maps two contacts per account, verifies senior contacts by hand before the first call, and hands the complete list and all CRM records to the client at exit. We do not resell data. See our lead generation service.

The bottom line

The list is 60 percent of an outbound program's performance. A real SDR agency builds it, verifies it and gives it back to you. If the proposal assumes you will supply the list, you are buying appointment setting, which is fine if your data is good and a problem if it is not. Ask the seven questions, look at a sample, and put ownership in the contract.

Want to see a sample list built against your ICP before you commit? Book a 15 minute call.

Frequently asked questions

Do SDR agencies build their own prospect lists? A genuine outsourced SDR agency does, from the ICP you supply, using several data sources and hand verification for senior contacts. Agencies that only call your list are providing appointment setting.

Who owns the prospect list in an outsourced SDR engagement? You should. The contract should state that the account list, contact records, enrichment and CRM records are yours and are handed over at exit, and that any data licence terms permit the transfer.

What data sources do SDR agencies use in Australia? Typically an Australian native platform for phone data (local providers outperform global platforms on Australian mobile coverage), a global platform such as Apollo, ZoomInfo or Cognism for breadth and email, and LinkedIn Sales Navigator for current titles.

Can I give my SDR agency my own list? Yes, and the best use of it is usually as a set of target accounts around which the agency rebuilds the contacts. Client supplied lists are frequently stale, thin on phone numbers and include existing customers.

How often should a prospect list be refreshed? Daily verification of the next accounts to be called, re verification of anyone not reached in 90 days, and a quarterly rebuild of the account tier. B2B contact data decays at roughly 3 percent a month.

How long does it take an SDR agency to build a prospect list? About two weeks for 1,500 to 3,000 accounts with two verified contacts each: two days translating the ICP into criteria, three days building the account universe, three days mapping contacts, three days sourcing phones and emails, a day of suppressions, and two days of sample review and loading.

What should be in a suppression file for an outbound campaign? Current customers by ABN and domain, open opportunities, recent closed lost deals, do not contact requests, competitors, partners and referrers, and any consumer numbers flagged by a Do Not Call Register wash. The client supplies customers, opportunities and partners; the agency handles the rest. Refresh monthly.

Sources and references

1. SyncGTM. 6 Best B2B Databases for Australia in 2026. https://syncgtm.com/blog/best-b2b-database-australia ; SMARTe. "Best B2B Data Providers in Australia for 2026.".
2. Salesmotion. Best B2B Contact Data Providers in 2026 (Compared). (Approximately 3 percent monthly decay, citing Gartner.).
3. Nousu Collective. How to Build an ICP for B2B Outbound.