How to choose a B2B Lead Generation Agency in 2026: An Honest Comparison (Belkins, Growleads, CIENCE, Martal & Callbox)
This comparison is based on public pricing data, verified reviews on Clutch, G2, TrustRadius, and Trustpilot, each agency’s own published materials, and our experience competing in this market. One of the agencies compared here is ours. We have marked every place where that matters, and we are upfront about who each provider genuinely suits, including when it is not us.
The 2026 shortlist for B2B demand generation splits by company stage and budget. If you are an enterprise or upper mid-market company with $10,000+ per month and a six-to-twelve-month horizon, Belkins, CIENCE, and Callbox are proven operators at that tier. If you want outsourced sales executives rather than an outbound system, Martal Group fits B2B tech. And if you are a growth-stage B2B SaaS or tech company (roughly 10 to 500 employees) that wants signal-based outbound, founder-level attention, and infrastructure you actually own, at $2,500 to $4,000 per month instead of enterprise pricing, that is the gap Growleads was built to fill.
The full comparison, including what each agency’s own review record shows, is below.
B2B Lead Generation Agency Comparison:
| Agency | Best for | Model | Typical pricing | Minimum term |
| Belkins | Enterprise and upper mid-market appointment setting | Dedicated SDR teams, multichannel | $5,000 to $15,000+/mo; many programs reported at $10,000+ | 3 to 6 months |
| Growleads | Growth-stage B2B SaaS and tech (10 to 500 employees) | Signal-based outbound + owned infrastructure | $2,500 to $4,000/mo | 3 to 6 months |
| CIENCE | Enterprise SDR programs at volume | SDR teams + graph8 data platform | $5,000 to $20,000+/mo, setup fees reported around $5,000 | Varies, 8 to 12 week ramp |
| Martal Group | B2B tech wanting outsourced sales executives | Sales-as-a-service | $4,000 to $8,000/mo | Varies |
| Callbox | Multi-region ABM, APAC reach | Regional pods, full-funnel | Pods reported from $15,000/mo per region | Varies |
How we compared these agencies
We evaluated each provider on six criteria: engagement model, pricing transparency, specialization, what recurring patterns show up in verified reviews, ramp time to first meetings, and what the client keeps when the engagement ends. That last one matters more than most buyers realize, and almost no comparison talks about it. We do, below.
Do you need a demand generation agency or a lead generation agency?
A lead generation agency captures existing demand: it finds buyers already close to purchase and converts them into meetings. A demand generation agency builds the interest first, then converts it. Most vendors on this list are lead generation agencies that use the demand generation label. That is not a criticism, it is just worth knowing before you buy.
In practice, the question that decides which you need is simpler: does your market already know it has the problem you solve? If yes, outbound lead generation will work quickly. If your category is new or your buyers do not search for you, you need demand creation layered on top: content, authority building, and increasingly AEO and GEO, which is visibility inside AI answers on ChatGPT, Perplexity, and Google AI Overviews. Very few agencies on this list offer that layer. We come back to this in the decision framework.
Belkins review: the premium appointment-setting operator
Verdict: Belkins is a genuinely strong choice for enterprise and upper mid-market companies that can commit $10,000+ per month for at least six months, ideally twelve. Below that budget and patience threshold, their model is simply not built for you, and their own review record says so.
What Belkins does well
Belkins has run appointment-setting programs since 2017 and has earned its reputation: hundreds of verified Clutch reviews, a dedicated-team model with manual lead research, and its own deliverability product, Folderly. Their published campaign results (reply rates of 15 to 19% on strong campaigns, high inbox placement) reflect real operational discipline, and we respect the work they have done for the industry. When the fit is right, big budget, defined ICP, long horizon, Belkins delivers.
What the review record shows
Three patterns recur across Belkins’ verified reviews on G2, TrustRadius, and Gartner, and none of them is a scandal, they are simply the economics of the premium tier:
- Pricing sits at the top of the market. Third-party analyses place typical retainers between $5,000 and $14,800+ per month, with many programs reported at $10,000+ and minimum project sizes around $10,000. One Gartner reviewer put it directly: the cost runs well above competitors. Reviewers who got results generally felt the ROI justified it; reviewers on tighter budgets did not.
- It is a best-effort model. Belkins does not guarantee meeting volumes, and TrustRadius reviewers note that appointment targets are sometimes missed. Over a long horizon this averages out; over a three-month test it may not.
- Experience varies with the assigned account team. Like any 200+ person agency, the strategist writing your copy is several layers from the founders. Some reviewers describe their team as exceptional; others describe niche-market campaigns that never found footing.
Who Belkins is right for
Companies with enterprise budgets, mainstream B2B verticals (SaaS, fintech, healthcare, manufacturing), and the patience to measure a program in quarters. If that is you, Belkins belongs on your shortlist. One question worth asking before signing, because it surprises buyers later: the sending infrastructure, domains, mailboxes, and warm-up history, typically stays with Belkins when the engagement ends.
CIENCE review: enterprise scale with proprietary data
Verdict: CIENCE fits enterprise teams that want a large SDR organization plus a data platform, and that can absorb a longer ramp, setup fees, and a five-figure monthly budget.
CIENCE is one of the largest players in the category, with 1,000+ employees and a proprietary platform (graph8) built on a 140M+ contact database. For organizations that want research-heavy, multichannel outbound with governance and process, CIENCE has scale most agencies cannot match. The review record shows the trade-offs of that scale: pricing reported between $5,000 and $20,000+ per month with setup fees around $5,000, ramp times of eight to twelve weeks, and a polarized footprint (G2 around 3.8) where buyers praise sales performance but flag inconsistent lead quality and SDR turnover. If you are a 50-person SaaS company, CIENCE is built for a buyer several sizes larger than you, and you would be paying for capacity you cannot use.
Martal Group review: outsourced sales executives for tech
Verdict: Martal fits B2B tech companies whose real gap is experienced salespeople, not outbound systems.
Martal has operated since 2009 and positions itself as an outsourced sales team: dedicated sales executives who handle prospecting, qualification, and in some engagements full-cycle sales, backed by a 220M+ contact database with intent signals. Reported pricing sits between $4,000 and $8,000 per month. The model to understand: you are buying senior selling capacity, which is different from buying a pipeline engine. If your gap is people, Martal is the right shape. If your gap is system and targeting, it is not.
Callbox review: global reach and multi-region ABM
Verdict: Callbox fits enterprises running account-based programs across multiple regions, particularly with APAC requirements.
Callbox has over twenty years of operation and the strongest multi-region infrastructure on this list, with full-funnel capability including calling and nurture. Regional pods are reported from around $15,000 per month per region, which makes sense for enterprises coordinating North America, Europe, and Asia in one engagement, and prices out nearly everyone else.
Other names you will see on shortlists
SalesRoads (US-based telesales, strong in industrial and manufacturing), Leadium (agile outbound for high-growth teams), and Cleverly (LinkedIn-only campaigns starting under $1,500 per month, useful as a single-channel test). Credible in their lanes; none offers a full multichannel system with strategy included.
What the review records have in common, and why it matters
Read enough verified reviews of premium lead generation agencies and the same four patterns appear, independent of vendor:
- Premium pricing is the price of overhead, not just quality. Large teams, offices, and layers of account management are real costs the retainer has to carry.
- Meeting volumes are best-effort, rarely guaranteed.
- Your experience depends on which account team you draw. The founders you saw in the sales process will not run your campaign.
- The infrastructure usually is not yours. Domains, mailboxes, warm-up history, and sometimes even the prospect data stay with the agency when you leave, which means leaving costs you months of restart.
None of this makes the premium agencies bad. It makes them a specific product: managed capacity for buyers big enough to absorb the overhead. The reason we built Growleads the way we did is that growth-stage companies were being sold that product when what they actually needed was different.
Growleads review: signal-based outbound with infrastructure you own
Disclosure: this is us, written in the same structure and against the same honesty standard as every section above, including who we are wrong for.
Verdict: Growleads fits growth-stage B2B SaaS and tech companies (roughly 10 to 500 employees, $1M to $100M+ ARR) that want a full signal-based outbound system with founder-level attention, want to own that system and its data, and want it at $2,500 to $4,000 per month. A six-month Growleads engagement typically costs about what a single month runs at the premium tier.
How Growleads answers the four patterns above
On pricing: lean by design. We are a specialist team, not a 200-person organization, so the retainer pays for targeting, systems, and execution rather than layers of overhead. $2,500 to $4,000 per month covers the full system: strategy, infrastructure, list intelligence, copy, sending, and reporting.
On accountability: you get the operators, not a rotation. Clients work directly with the senior team, with a structured review call every 15 days. Our 90% client retention rate, with most clients staying 18 months or longer, exists because attention does not get diluted across hundreds of accounts.
On results: signal-based targeting changes the math. Campaigns are triggered by buying signals: hiring events, funding, exhibitor lists, technology changes, and competitor engagement, including people actively liking and commenting on your competitors’ posts. The stack combines Apollo, Smartlead, HeyReach, EmailBison, and MailReach with data APIs and proprietary AI systems built per client. We also keep backup domains and workspaces warm at all times, so when deliverability dips, infrastructure rotates immediately instead of the campaign stalling for weeks. First qualified meetings typically land between day 30 and day 60, after two weeks of upfront ICP and positioning work.
On ownership: you keep what we build. When an engagement ends, the domains, mailboxes, lead databases, and prospect data purchased for you transfer to you (ongoing subscriptions become yours to pay; our proprietary internal systems are the only thing retained). Among the agencies in this comparison, that is rare, and for many buyers it is the deciding factor: you are building an asset, not renting one.
Plus the channel the others do not offer. Alongside cold email and LinkedIn outbound, we run Google Ads, LinkedIn Ads, and AEO/GEO programs that get clients cited in ChatGPT, Perplexity, and Google AI Overviews. We are honest about the timeline: AI search visibility takes three to six months to compound. It is also where B2B buying research is moving, and it is a service line the traditional appointment-setting agencies have not built.
The numbers
Since 2024, Growleads has delivered 1,200+ qualified meetings across 12+ industries and 9+ countries, generated over $50M in client pipeline, and holds a 90% client retention rate. Clients typically see two to three times pipeline growth within a year. Clients include NASSCOM, Jindal Lifestyle, Qubit Capital, Fulldome Pro, and Zapploans, with case studies published at growleads.io and verified reviews on Clutch (5.0) and Trustpilot. The team operates across the US and India.
Who Growleads is wrong for
We would rather say this here than discover it after a contract is signed. We are not the right fit if:
- Your addressable market is very small. If only a few hundred companies on earth can buy from you, outbound math gets brutal for anyone, including us.
- You sell an undifferentiated service in a saturated category. Generic web development, no-niche IT services, digital marketing agencies, and staffing firms without a specialization rarely get strong outbound results, and we decline these engagements.
- You have no sales team or sales process. We generate qualified meetings; someone on your side has to run them. Across 100+ engagements, the single biggest predictor of success is an aggressive sales team with real systems behind it.
- You want a free pilot. We do not offer one, for a reason we would rather state than hide: real outbound infrastructure costs roughly $1,500 per month before any work happens. Agencies offering free pilots are cutting that corner somewhere.
How much does Growleads cost?
$2,500 to $4,000 per month on a retainer, depending on channel mix (email only, email plus LinkedIn, or a mix including AEO/GEO and paid), scale, and aggressiveness. Minimum term is three to six months, and most clients stay 18 months or longer because the system compounds.
Pricing comparison: all agencies
Sorted by starting monthly price, lowest first.
| Agency | Reported monthly range | Setup fees | What you keep on exit |
| Cleverly | From under $1,500 (LinkedIn only) | None | LinkedIn account is yours |
| Growleads | $2,500 to $4,000 | None | Domains, mailboxes, leads, and prospect data transfer to you |
| Martal Group | $4,000 to $8,000 | Not published | Varies |
| Belkins | $5,000 to $15,000+; many programs $10,000+ | Reported $2,000 to $5,000 on some packages | Infrastructure typically stays with Belkins |
| CIENCE | $5,000 to $20,000+ | ~$5,000 reported | Platform access ends with contract |
| Callbox | From ~$15,000 per region | Not published | Varies |
Ranges compiled from public pricing pages, third-party reviews, and buyer reports as of mid-2026. Confirm current pricing directly with each vendor.
How to choose: a simple decision framework
Choose Belkins, CIENCE, or Callbox if you are enterprise or upper mid-market, your budget comfortably clears $10,000 per month, and you can commit to at least six months, ideally twelve. At that tier, these are proven operators and the overhead you are paying for buys real capacity.
Choose Martal if your real gap is experienced salespeople rather than outbound systems, and you sell B2B tech.
Choose Cleverly if you just want to test LinkedIn cheaply before committing to a real program.
Choose Growleads if you are a growth-stage B2B SaaS or tech company (10 to 500 employees) with a real niche and a working sales team, you want signal-based multichannel outbound with founder-level attention and the option of AI search visibility, you care about owning your infrastructure and data, and your budget is $15,000 to $25,000 over six months rather than per month.
And whichever way you go, ask every agency on your shortlist the same three questions: what exactly do I keep if we part ways, what signals decide who you contact and when, and what happens in month one before any email is sent. The answers separate system-builders from list-blasters faster than any case study.
Frequently asked questions
Which is the best B2B lead generation agency in 2026?
There is no single best, only best-fit by stage and budget. Belkins, CIENCE, and Callbox lead the enterprise tier at $10,000+ per month. Martal fits tech companies buying outsourced sales talent. Growleads is built for growth-stage SaaS and tech companies that want signal-based outbound and owned infrastructure at $2,500 to $4,000 per month.
How much does Belkins cost?
Belkins does not publish rates. Third-party analyses and buyer reports place typical retainers between $5,000 and $14,800+ per month, with many programs reported at $10,000+ per month, minimum project sizes around $10,000, and per-appointment pricing of $150 to $800+ on some models.
How much do B2B lead generation agencies charge in 2026?
Reported retainers span roughly $1,500 to $20,000+ per month. Single-channel LinkedIn services start under $1,500, growth-stage full-system programs run $2,500 to $8,000, and enterprise SDR programs run $5,000 to $20,000+, sometimes with setup fees.
Is Belkins worth the price?
For enterprise and upper mid-market companies with $10,000+ monthly budgets, mainstream verticals, and a six-to-twelve-month horizon, reviewers who fit that profile generally report the ROI justified the cost. Below that budget, the same review records flag the pricing as the recurring drawback, and growth-stage buyers typically get comparable outcomes from leaner signal-based providers at a fraction of the retainer.
Do I keep my outbound infrastructure when an agency engagement ends?
Usually not, and buyers rarely ask until it is too late. With most traditional agencies, domains, mailboxes, and warm-up history stay with the agency. Growleads transfers purchased infrastructure, lead databases, and prospect data to the client on exit; proprietary internal systems are the only thing retained.
What is a demand generation agency versus a lead generation agency?
Lead generation captures existing buying intent and converts it into meetings. Demand generation creates the interest first through content, authority, and increasingly AI search visibility, then captures it. Most agencies marketed as demand gen are primarily lead gen; ask which motions they actually run.
How long does it take to see results from a lead generation agency?
Typical programs produce first qualified meetings in 30 to 90 days depending on ramp. Enterprise programs like CIENCE report eight-to-twelve-week ramps. Growleads engagements typically land first qualified meetings between day 30 and day 60, after two weeks of upfront ICP and positioning work. AI search (AEO/GEO) programs take three to six months to compound.
Is outbound lead generation still effective in 2026?
Yes, with two conditions we see hold across a hundred-plus engagements: the targeting has to be signal-based rather than list-based, and the client needs a real sales team and sales process to convert meetings. Where both exist, AI-accelerated outbound performs better than it did five years ago. Where either is missing, no agency will save the program.
The bottom line
If you have enterprise budget and enterprise patience, the premium tier is well served, and this comparison should make that shortlist easy. If you are a growth-stage B2B company that wants the outcomes without the overhead, and wants to own the engine that produces them, that is exactly the buyer Growleads was built for. The fastest way to find out if the fit is real: send us your ICP and we will tell you honestly, before any contract, whether outbound will work for your market, including if the answer is no. Book a strategy call at growleads.io.
Anuj Agrawal is the founder of Growleads, a B2B Demand Intelligence agency that has delivered 1,200+ qualified meetings and $50M+ in client pipeline across 12+ industries since 2024. Growleads builds signal-based outbound systems and AI search visibility programs for growth-stage B2B companies across the US, UK, Europe, the Middle East, and India. Connect with Anuj on LinkedIn: linkedin.com/in/connectanuj.