HOW TO CHOOSE AN OUTSOURCED SALES DEVELOPMENT AGENCY
When scaling a B2B company, there comes a point where revenue leaders need to increase pipeline and face a choice: build a sales development function internally, or outsource to a specialist agency. There are pros and cons to both depending on many variables, and there are advantages to running the two alongside each other.
Unfortunately, too often sales and marketing leaders say they've had their fingers burnt with agencies that promise the world and spectacularly underdeliver. High activity, low quality. Hundreds of dials, very few conversations. Meetings booked that go nowhere.
The problem isn't usually the SDR. It's what the SDR is working with.
In this blog, we look at what separates the agencies that consistently deliver from those that don't, and what to look for when choosing a partner.
"The problem isn't usually the SDR. It's what the SDR is working with."
Start With Your Objectives
When choosing an outsourced sales development agency, it is important to be clear on your objectives and what success looks like from an engagement.
Are you a startup taking your value proposition to market from an outbound perspective for the first time? Or are you an experienced scale-up that already knows the message resonates and just needs more bandwidth to penetrate accounts?
A startup may be more interested in market feedback, the voice of the customer, and how messaging is resonating. A scale-up probably already knows this and needs an engine that can execute a proven playbook at scale.
Being clear on your objectives allows you to understand what is key from an agency. The question to ask is: what does success look like for us in the first 90 days?
The People
One of the most important things in an outsourced sales development agency is its people.
There is a belief that SDRs should have several years of experience, but this doesn't always align with the best results. Typically, the natural next step and often the goal for an SDR is to become an AE, so experienced SDRs are often already looking to make that transition. Alternatively, they may not have progressed due to their performance so far. Neither is ideal when you're paying for someone to represent your brand on the phone.
Look for SDRs who have had enough time to onboard, ramp, and find their feet, but are still motivated, energised, and have something to prove. Often, the best outsourced SDRs are people who have some experience in a sales capacity and are transferring those skills to sales development.
Other things to consider:
How are they recruited?
How are they onboarded?
How are they continuously trained and educated on sales techniques?
What is their knowledge of your industry and target market?
How does the agency incentivise SDR performance?
But here's the thing most agencies get wrong: even the best SDR in the world will underperform if the data they're working from is bad.
The Data Problem Nobody Talks About
This is where the majority of outsourced sales development programmes fall down, and very few agencies address it properly.
Most agencies will take your ICP, pull a list from an enrichment tool, and hand it to their SDR to start dialling. The problem is that 20-30% of that data is incorrect before the first call is ever made. Wrong numbers, people who've changed roles, contacts who left the company months ago. And the data decays at roughly 3% per month, so a list that was accurate in January is meaningfully different by June.
If your SDR is getting a 10% pick-up rate, it's not really 10%. Once you strip out the wrong numbers and changed roles, it's probably closer to 6-7%. So out of 80 calls a day, they're having maybe 5 meaningful conversations. The rest is voicemails, dead lines, and wrong people.
That's not a performance problem. That's a data problem.
When evaluating an agency, ask them: how do you build and verify the data your SDRs are calling from? If the answer is "we pull it from an enrichment tool," push deeper. That's what everyone does. The question is what happens after that.
The agencies that consistently deliver are the ones that have invested in a data function that sits underneath the SDR. A team whose sole responsibility is to map accounts, find the right decision makers, enrich the data from multiple sources, and then verify it through real phone calls. Not a database lookup. A real conversation that confirms the person is still in the role, the number works, and they're reachable.
When you do that, pick-up rates improve dramatically. Your SDR isn't wasting half their day on dead dials. They're calling people who actually answer. More conversations from fewer calls. That changes everything.
"That's not a performance problem. That's a data problem."
Empowering the SDR to Succeed
The best outsourced sales development agencies don't just give their SDRs a list and a script. They set them up to have the best possible conversation with every person they speak to.
That means three things.
First, the SDR knows which accounts to focus on. Not a random list of 500 companies that match a firmographic filter, but accounts that have been specifically identified and prioritised because something is happening inside them. A new hire, a leadership change, a competitive shift, a growth indicator. Something that gives the SDR a reason to call today versus any other day.
Second, the SDR knows the person will pick up. Because the data has been verified. They're not guessing whether the number works. They know.
Third, the SDR has context for the conversation. Not just a name and a title, but intelligence about what the prospect cares about, what's happening in their world, and how to make the conversation relevant from the first 10 seconds.
When an SDR has all three of those things, the conversation changes completely. They're not making a cold call. They're making an informed, relevant call to someone who will actually answer. That's the difference between an SDR who books meetings and an SDR who burns through a list.
"They're not making a cold call. They're making an informed, relevant call to someone who will actually answer."
Collaboration and Partnership
A successful outsourced sales development initiative hinges on the relationship between the client and the agency.
It is imperative that the agency works as an extension of your sales and marketing teams. It should never be viewed as set and forget. You can't just hand over the messaging and expect pipeline.
The agency is your eyes and ears in the market. They should feel comfortable explaining problems openly and making suggestions based on what they're hearing from prospects.
In order to drive positive collaboration and a healthy partnership, think about:
A structured onboarding process to understand your business, target audience, and objectives
Detailed weekly and monthly reports that include key metrics, call recordings, campaign performance insights, and market feedback
A feedback loop between the client and agency to share meeting feedback, lead handover quality, what is working, and areas to improve
A single point of contact to ensure clear communication, alignment, and a point of escalation
The best campaigns are the ones where the SDR has a direct relationship with your AEs. When an SDR can go to your AE and say "I just had this conversation, they mentioned X, can you follow up with Y?" that's when outbound becomes a real extension of your sales function, not just a meeting machine.
The Approach
When choosing an outsourced agency, it is important to choose a company that aligns not just with your objectives, but with the approach you want to implement.
Many agencies generate meetings through email and automation. Some rely heavily on LinkedIn. Others are phone-first.
We'd always recommend an agency that takes an account-based approach and is proficient across telephone, email, and LinkedIn, but leads with the phone. If you can get someone on the phone, you can have a conversation, probe, qualify, and build rapport. You can't do that in an email.
About 80% of meetings in a well-run outbound programme come from the telephone. Email and LinkedIn support the phone. They don't replace it.
A key factor here is having a team operating in your prospect's time zone, with a relatable accent for your target market. A UK-based SDR calling into the US Midwest is going to have a different reception than someone local. That matters more than most agencies admit.
"Email and LinkedIn support the phone. They don't replace it."
Alignment on KPIs
Traditionally, revenue leaders have measured SDR performance on the number of meetings booked. However, not all meetings hold the same value, and this can incentivise the wrong behaviour if the right expectations are not set.
If your outsourced provider relies on aggressive tactics to target poorly matched prospects, you may end up with plenty of meetings that have little impact on your revenue number.
The better metric is what we'd call a Sales Accepted Lead: a meeting with a time and date in the agenda, within an agreed target account, with an agreed target persona, who has a relevant pain, need, or interest in learning more about the solution. That definition should be agreed before the programme starts, not debated after the first month.
Other things worth measuring:
Conversations per day, not dials. If your SDR is having 8-10 meaningful conversations a day from verified data, that tells you more than knowing they made 80 calls. Dials without conversations is just noise.
Pipeline generated, not just meetings booked. Meetings are the input. Pipeline is the output. A meeting that creates £50K in pipeline is worth more than five meetings that go nowhere.
Quality of handover. When a meeting is booked, does the SDR provide context on the conversation? Do they share what was discussed, what the prospect cares about, and what the expected next steps are? Or do they just throw a calendar invite over the fence? The handover process tells you a lot about how an agency operates.
To promote a more effective strategy, align ahead of time on expectations of how many meetings will be generated, the percentage that should convert to pipeline, the attendance rate, and the KPIs that will drive genuine collaboration.
Investment Models
The approach you want will ultimately have a knock-on effect on the price and investment model.
A team of local SDRs working from verified data with account-level intelligence will be more expensive than a heavily automated approach. But it will also drive better quality meetings and pipeline.
A few things to think about:
Understand what's included in the pricing. Hidden costs can add up over time. Is the data build included? Is account mapping included? Or are those charged separately?
Don't just look at the cheapest option. Consider how the agency aligns with the approach you want, your long-term goals, and the ROI. The cheapest option is rarely the best when it comes to outbound.
Some agencies offer shortened engagements to prove value before committing to longer-term contracts. This has positives, but it also limits the return you'll see in a short window. Outbound takes time to ramp, and judging a programme on the first 30 days rarely gives you the full picture.
Ask about the data investment. Agencies that invest in mapping, verifying, and prioritising accounts before the SDR picks up the phone typically cost more upfront but deliver significantly better results over time.
Red Flags to Watch For
A few things that should give you pause when evaluating agencies:
Leading with automation and volume. If the pitch is "we'll send 10,000 emails a month," that should raise questions. Buyers are overwhelmed. Inboxes are flooded. Volume without quality is just noise.
No data process. If they can't explain how they build, verify, and maintain the data their SDRs call from, the data process probably doesn't exist. That means your SDR is calling from the same enrichment lists everyone else uses.
Constantly changing SDRs. High turnover disrupts continuity, kills momentum, and impacts results. Ask about SDR tenure and how they retain their team.
Operating in a black box. If they don't share processes, data, call recordings, or market feedback, that's a sign of trouble.
Lack of industry experience. Especially with longer, more complex sales cycles and value propositions. Selling a £5K product is very different from selling a £500K platform.
Focus on quantity over quality. Activity metrics that emphasise dials and emails sent rather than conversations and pipeline generated.
Slow response times or lack of regular updates. If communication is poor during the sales process, it won't improve once they have your money.
What to Look For
The best outsourced sales development agencies share a few common traits:
They invest in the data before the SDR picks up the phone. Account mapping, contact enrichment, manual verification. The hard work happens before the first dial, not during it. The SDR's job is to have conversations, not to research accounts and chase wrong numbers.
They empower their SDRs with context and intelligence. The SDR knows why they're calling this account today, who they're speaking to, and what to say. Every conversation is relevant.
They lead with the phone but support with email and LinkedIn. Multi-channel, not multi-spam.
They work as an extension of your team. Honest feedback, transparent reporting, genuine partnership. The best agencies want to hear what's working and what's not, and they adjust accordingly.
They measure quality over quantity. Sales Accepted Leads, pipeline generated, and conversations per day matter more than dials and emails sent.
They iterate and improve. The programme in month three should be measurably better than month one. The data improves, the messaging tightens, and the team learns what works for your specific market. The intelligence compounds over time.
Final Thoughts
Choosing an outsourced sales development agency is one of the most impactful decisions a revenue leader can make. Get it right and you've got a pipeline engine that compounds over time. Get it wrong and you've burnt budget, damaged your brand in the market, and lost months you can't get back.
While outsourcing can unlock efficiencies, bring in fresh expertise, and allow you to scale faster, choosing the wrong agency can waste resources and leave you frustrated.
By investing time upfront to understand the people, the data process, the approach, and the partnership model, you can avoid the pitfalls many leaders have experienced and instead create a lasting partnership that drives meaningful pipeline growth.
The agencies that consistently deliver are the ones that have solved the data problem, empowered their SDRs to have better conversations, and built genuine partnerships with their clients. Everything else is noise.
