Shortlist methodology
A useful outsourced SDR shortlist should include providers whose operating model matches the work you need owned. The eight researched providers in this guide are grouped alphabetically and by buyer need, not ranked: Belkins, Callbox, CIENCE, Leadium, Martal Group, memoryBlue, SalesHive and SalesRoads. Verify team allocation, qualification, CRM ownership, commercial terms and the work performed after meetings before choosing.
Key takeaways
- No provider is best for every buyer.
- Operating-model fit matters more than list position.
- Public pricing is too inconsistent for a defensible market average.
- Internal and hybrid SDR models belong in the same decision.
| Provider | Public operating direction | Buyer-fit question |
|---|---|---|
| Overland GTM | Founder-led managed GTM operating system | B2B companies that need strategy, research, outbound execution, calling, qualification, CRM operation and weekly learning connected in one managed scope. |
| Belkins | Appointment setting and outbound services | Teams seeking a specialist appointment-setting programme with supporting research and outreach services. |
| SalesRoads | US-based outsourced SDR and appointment setting | Teams prioritising US-based phone-led sales development and a dedicated outsourced SDR programme. |
| Martal Group | B2B lead generation and sales outsourcing | Technology companies seeking an externally operated prospecting and sales-development team across North American and international markets. |
| SalesHive | Outsourced SDR and appointment setting | US-focused teams comparing modular outbound programmes with calling, email and list-building support. |
| memoryBlue | Outsourced technology sales development | Technology companies that value SDR talent development, managed prospecting and a route to internal talent transfer. |
| Leadium | Lead generation, data and outsourced SDR | Teams looking for prospect data, outbound execution and SDR support in one provider relationship. |
| Callbox | Multi-channel B2B lead generation and appointment setting | Companies seeking broad international coverage and a multi-channel campaign model. |
| CIENCE | Managed B2B lead generation and GTM execution | Teams evaluating a technology-enabled managed outbound programme with data, campaign and SDR components. |
Overland GTM
Founder-led managed GTM operating system
B2B companies that need strategy, research, outbound execution, calling, qualification, CRM operation and weekly learning connected in one managed scope.
Belkins
Appointment setting and outbound services
Teams seeking a specialist appointment-setting programme with supporting research and outreach services.
SalesRoads
US-based outsourced SDR and appointment setting
Teams prioritising US-based phone-led sales development and a dedicated outsourced SDR programme.
Martal Group
B2B lead generation and sales outsourcing
Technology companies seeking an externally operated prospecting and sales-development team across North American and international markets.
SalesHive
Outsourced SDR and appointment setting
US-focused teams comparing modular outbound programmes with calling, email and list-building support.
memoryBlue
Outsourced technology sales development
Technology companies that value SDR talent development, managed prospecting and a route to internal talent transfer.
Leadium
Lead generation, data and outsourced SDR
Teams looking for prospect data, outbound execution and SDR support in one provider relationship.
Callbox
Multi-channel B2B lead generation and appointment setting
Companies seeking broad international coverage and a multi-channel campaign model.
CIENCE
Managed B2B lead generation and GTM execution
Teams evaluating a technology-enabled managed outbound programme with data, campaign and SDR components.
How providers qualify for this guide
A provider must be active, materially relevant and supported by enough current official evidence to describe its operating direction fairly. Inclusion is not endorsement. Providers appear alphabetically, not by score, commission or commercial relationship.
Shortlist by buyer need
Appointment-setting specialism: Belkins and SalesRoads. Modular outsourced SDR programmes with public commercial guidance: SalesHive and Leadium. Technology-sales specialism: Martal Group and memoryBlue. Broad multi-channel or technology-enabled delivery: Callbox and CIENCE. These are directional groupings, not exclusive claims.
Why there is no market-average price
Public commercial information is not sufficiently standardised. A monthly figure can represent different SDR allocation, research, data, calling, email infrastructure, management, onboarding, qualification and meeting policies. Use official pricing where available, then normalise scope in writing.
The evaluation questions that change the decision
Ask who performs each part of the motion and what happens when market evidence contradicts the original brief.
- Is capacity dedicated, named, pooled or usage-based?
- Who owns data, domains, CRM records and suppression?
- How are meetings accepted, rejected and replaced?
- Who handles replies, qualification and no-shows?
- How does learning change targeting and messaging?
- What are the minimum term, exit and handback conditions?
Publisher disclosure
Overland GTM publishes this research and is a commercial alternative in this market. Providers do not pay for inclusion or position. We use official provider pages for volatile claims, identify unknowns and do not assign rankings, ratings or universal winners.
Sources & verification
These first-party pages support material claims in this comparison. Product capabilities, packaging and commercial terms can change, so verify current scope directly before purchase. Claims were last checked on .
- Overland GTM: Overland GTM EngineAccessed 2026-08-21
- Belkins: Belkins homepageAccessed 2026-08-21
- SalesRoads: SalesRoads homepageAccessed 2026-08-21
- Martal Group: Martal homepageAccessed 2026-08-21
- SalesHive: SalesHive homepageAccessed 2026-08-21
- memoryBlue: memoryBlue homepageAccessed 2026-08-21
- Leadium: Leadium homepageAccessed 2026-08-21
- Callbox: Callbox homepageAccessed 2026-08-21
- CIENCE: CIENCE homepageAccessed 2026-08-21
Frequently asked questions
What are the best outsourced SDR companies?
There is no universal best. This guide researches Belkins, Callbox, CIENCE, Leadium, Martal Group, memoryBlue, SalesHive and SalesRoads because current official evidence supports useful comparison.
How should providers be shortlisted?
Start with the responsibility boundary, buyer geography, channel needs, team allocation, qualification, CRM ownership, internal management and commercial terms.
Why are providers alphabetical?
Alphabetical presentation avoids implying a ranking that the evidence cannot support.
Is Overland included?
Overland is the publisher and a commercial alternative. It is disclosed separately rather than inserted into the alphabetical provider table as an impartial recommendation.
Written by
Antonio Davenia
Founder, Overland GTMA founder-led operating partner for international B2B companies entering priority markets.
About Antonio