Go-to-Market
Kayla Tait
October 21, 2026
New York ranks second in the global startup ecosystem, according to Startup Genome. This makes the city a competitive place for B2B companies to position themselves and their services. But outbound only works when somebody follows up consistently, and many teams find that hard to staff. This is where outsourced sales development comes in.
If you’re wondering what outsourced sales means? Instead of building every part of a sales development function in-house, a company partners with an external provider to handle some or all of its prospecting and lead-generation activities. Depending on the arrangement, this can include researching ideal customer profiles (ICPs), sourcing contact data, writing messaging, running cold calls and email or LinkedIn sequences, qualifying leads, booking meetings and reporting on performance.
Some outsourced sales development agencies provide a fully managed service, taking responsibility for strategy and execution. Others place SDRs within your existing team or help you build the systems your internal representatives need to succeed. Supporting services may include CRM management, sales training, account-based marketing and revenue operations.
The right option depends on your sales team's capacity, the maturity of your go-to-market strategy and how much execution you want to outsource. This list compares 10 providers on their service models, specialisations and suitability for different B2B businesses.
The answer to this depends on the model you need. Sales development outsourcing companies fall into several groups, so the table shows how each one works.
Alt text: Whistle homepage showing outsourced sales development through managed SDR and hire SDR offerings.
Whistle has two distinct offerings for companies to choose from. Outsourced SDR is a done-for-you programme. It comes with an SDR team, a dedicated customer success manager, a team lead, messaging, multi-channel sequences, contact data, a reporting dashboard and CRM integration support. It goes live in 10 business days, and your own sales team closes the meetings it books. The service covers prospecting and outreach across cold calling, cold email and LinkedIn. Whistle's team works to identify suitable prospects, execute outreach, optimise campaigns and report on performance, while the client's sales team focuses on progressing and closing opportunities.
Hire SDRs places a vetted SDR within your team. A suitable candidate is identified in under 24 hours, and an SDR is placed within five days, subject to client-side requirements and delays.
You retain day-to-day management of the representative, making this model more appropriate for businesses that want greater control over prospecting strategy and execution. Whistle also offers flexible arrangements, including month-to-month contracts for its Hire SDR service.
Whistle’s SDRs have five or more years of experience in sales, across phone, email and LinkedIn outreach, and offer coverage across various time zones and major languages. This allows outreach to run seamlessly during New York's working hours. Over 350 companies trust Whistle, and its published case studies report $11.4M in pipeline and 89x ROI for vcita, $32M and 186x for Shell, and $6.6M and 53x for Rezdy.
Additional services:
Beyond its two core offerings, Whistle provides supporting services that can address other gaps in the sales development process:
What they cover: Managed outsourced SDR programmes, SDR placements, cold calling, cold email, LinkedIn outreach, pipeline generation, contact data, HubSpot RevOps and conference lead generation.
Best for: B2B technology and SaaS companies that want a managed outbound function, need vetted SDR talent or require additional support across prospecting, data and sales operations.
Pricing: Contact Whistle for a quote based on the service and scope required.
Alt text: SalesCaptain homepage promoting B2B outbound and GTM services.
SalesCaptain operates across the USA, Canada, the UK, Europe and Asia and serves New York clients remotely. Their service is built on data and automation with prospect lists built from intent, funding and revenue data. They then run multi-channel campaigns through LinkedIn, email and text. They also offer CRM enrichment, inbound-led outbound and Clay and AI workflows, and connect with HubSpot and Salesforce.
What they cover: Outbound sales, inbound-led outbound, CRM enrichment, LinkedIn social selling, Clay and AI workflows, an AI GTM programme.
Best for: B2B teams that want email and LinkedIn-led outbound with enriched data, without hiring a BDR team.
Pricing: Contact SalesCaptain for pricing.
Alt text: Martal homepage describing its B2B lead generation and sales enablement service.
Martal offers fractional, full-time and enterprise team structures. Its service list covers appointment setting, cold calling, cold email, LinkedIn lead generation, inbound lead qualification and sales training. It also describes a sales outsourcing service that runs the cycle from prospecting to closing.
What they cover: B2B appointment setting, outbound lead generation, cold email, cold calling, LinkedIn lead generation, sales outsourcing, sales training.
Ideal for: Companies that want a sizeable onshore team and may later want the provider to take on closing.
Pricing: Contact Martal for pricing.
Alt text: Growth Alliance homepage for fractional advisory and revenue systems work.
Growth Alliance is about fractional advisory and engineering; serving $5M to $50M ARR B2B companies worldwide. Its services include outbound engine design with deliverability-first sequences, revenue operations, GTM architecture and account-based marketing.
What they cover: Outbound engine design, revenue operations, GTM system architecture, account-based marketing, AI-driven operations, fractional leadership.
Best for: Mid-market teams that have reps and need the outbound system around them.
Pricing: Contact Growth Alliance for pricing.
Alt text: Belkins homepage advertising B2B lead generation and appointment setting.
Belkins serves B2B clients through omnichannel outreach, with its headquarters in Dover, Delaware, with an office in Kyiv, Ukraine. It serves New York clients remotely. The team model pairs an account manager, an SDR, a lead researcher, a copywriter and an email specialist.
What they cover: Appointment setting, cold email, cold calling, LinkedIn lead generation, lead research, account-based marketing, deliverability consulting.
Best for: Companies that want a high meeting volume and a provider with a long client list.
Pricing: Contact Belkins for pricing.
Alt text: CrewBloom homepage for hiring remote sales and support staff.
CrewBloom is a remote staffing company that places sales, support and other professionals. This includes sales development representatives, business development representatives and inside sales reps. This is a staffing model, so you manage the SDR and own the strategy.
What they cover: Remote SDR, BDR and inside sales placement, plus support, admin, finance and IT roles.
Best for: Teams with a sales leader who can manage reps and want lower-cost remote capacity.
Pricing: Contact CrewBloom for pricing.
Alt text: Leadium homepage describing B2B lead generation and sales appointments.
Leadium runs managed SDR programmes across cold calling, email and LinkedIn.Their SDRs are senior and US-based and handle messaging, sequence strategy, lead data and the outreach itself. That is closer to a managed team than a staffing placement.
What they cover: Outbound appointment setting, lead research, messaging, cold calling, email and LinkedIn outreach.
Best for: Teams that want outsourced sales development with a dedicated, US-based SDR focused on cold calling.
Pricing: Contact Leadium for pricing.
Alt text: Ironpaper homepage for B2B growth and account-based marketing services.
Ironpaper is a B2B marketing agency that runs demand generation, account-based marketing, content and sales enablement for B2B companies, and it is a HubSpot partner.
What they cover: Demand generation, account-based marketing, B2B content, sales enablement, HubSpot services, web design.
Best for: New York B2B companies that want a local marketing partner for pipeline, with outbound handled elsewhere.
Pricing: Contact Ironpaper for pricing.
Alt text: Sales Empowerment Group page about its Power of One revenue generation approach.
Sales Empowerment Group’s model centres on outsourced revenue-generation teams, typically in 6 to 12 month engagements. They follow a revenue generation system that aligns marketing, sales talent, training and technology, and also offer interim sales leadership and sales coaching.
What they cover: Marketing services, sales talent and interim leadership, sales training and coaching, technology and CRM services, outsourced sales teams.
Best for: Mid-sized B2B companies that want outsourced sales teams, training and technology from one provider.
Pricing: Contact Sales Empowerment Group for pricing.
Alt text: LevelUp Leads homepage offering outsourced SDR and appointment setting.
LevelUp Leads functions as an extension of your team, with fractional or fully managed SDR options. A fractional model lets a smaller team start with part of an SDR before it commits to a full programme.
What they cover: Appointment setting, cold calling, cold email, LinkedIn outreach, list building, sales development strategy.
Best for: Early-stage startups and small businesses that want fractional or fully managed outsourced sales development.
Pricing: Contact LevelUp Leads for pricing.
The right partner depends on the gap you're trying to fill. Although many outsourced sales development agencies describe themselves as full-service providers, their operating models can be very different. Start by assessing the following factors.
If you need a complete outbound function, look for outsourced SDR services that include the people, messaging, data, campaign execution and reporting. A managed programme can reduce the burden on your internal team because the provider takes responsibility for coordinating these activities.
Outsourced SDRs is one option for businesses seeking this arrangement. If you already have a sales leader and established processes but need another representative, our Hire SDRs service offers an alternative through vetted SDR placements.
A provider should understand your target accounts, buyer personas, industry terminology and sales cycle. Ask how it researches prospects, validates contact information and adapts messaging to different segments. A large contact database is not enough if the people being contacted are unlikely to buy your product or service.
Compare the provider's approach to cold calling, email and LinkedIn outreach. Ask how it sequences these channels, personalises messaging, handles replies and follows up with prospects who do not respond immediately.
Our combination of managed SDR services and supporting outreach offerings is relevant to businesses that want to coordinate multiple channels. Our conference lead generation service may also be useful for companies whose prospecting strategy includes industry events.
Ask how the provider defines a qualified meeting, what happens when a meeting does not meet the agreed criteria, and how results are reported. Useful measures may include positive reply rates, meetings held, qualified opportunities, pipeline generated and conversion into later sales stages. No single metric tells the whole story. A high meeting count has limited value if prospects are poorly qualified or do not progress through the sales process.
Your provider should explain how prospect data enters your CRM, who maintains the records, how duplicate or inaccurate contacts are handled, and what happens to data and campaign assets when the engagement ends. If your CRM is a significant bottleneck, consider whether you need RevOps support alongside SDR execution. At Whistle, for example, we offer HubSpot-focused services covering data hygiene, process automation and reporting.
If you're selling to New York buyers, make sure the provider can execute outreach during appropriate US business hours. Ask where the SDRs are based, how coverage is scheduled, and how your internal team will receive updates. A provider does not necessarily need a New York office to serve the market effectively. Its actual coverage, buyer knowledge and ability to collaborate with your sales team are more important than its address.
Ask about onboarding fees, monthly costs, contract length, minimum staffing commitments and the process for increasing or reducing capacity. A managed programme and a placed SDR should not be compared on price alone. One may include management, data, technology and reporting, while the other may require your team to provide those resources. Compare the complete cost of achieving the outcome you need.
While there is no universally accepted definition of the 3-3-3 rule in sales, one commonly cited interpretation involves making three phone calls, sending three emails and using three social touches over three weeks. Treat this as a rule of thumb rather than a fixed formula. The appropriate number of touches depends on your audience, offer, industry, buying cycle and the responses you receive.
The principle is more useful as a way to assess an agency's follow-up process. Ask how many touches it typically plans, which channels it uses, how long a sequence runs and what happens when a prospect engages but is not ready to book a meeting. A good provider should be able to explain its approach and adjust it based on campaign performance. For example, our multichannel outreach services span phone, email and LinkedIn, while our conference lead generation offering can support outreach around specific events. For additional guidance on the email component, you can see our guide to prospecting follow-up emails.
An outside provider makes sense when one of these applies:
Choosing by office address and availability. Calling hours, English fluency and US buyer knowledge matter more than a postcode.
Skipping the definition of a qualified meeting. Agree in writing what counts, who accepts it and what happens when it does not meet the bar.
Outsourcing before the ICP is clear. A provider can scale what works. It cannot guess your buyer. Run some direct outbound first so you know who replies.
Ignoring who owns the data and tooling. Ask whether you keep the lists, sequences and domains if you leave.
Not asking about touch counts. Use the 3-3-3 test from earlier. Outsourced SDR services that drop a prospect after one email have not worked the account.
For New York businesses comparing outsourced sales development agencies, Whistle offers two core routes depending on how much of the sales development function they want to outsource.
Outsourced SDR is designed for businesses that need a managed SDR programme. It combines SDR execution with a team lead, dedicated customer success manager, messaging, contact data, multichannel sequences, reporting and CRM integration support. Whistle states that the programme can go live in 10 business days, allowing businesses to begin outbound activity without going through a full internal recruitment and setup process.
Hire SDR is designed for businesses that want to manage their own SDRs. It provides access to vetted sales development representatives, with candidate identification in as little as 24 hours and placement within five days, subject to client-side requirements. This option can suit teams that already have a defined go-to-market strategy but need additional capacity.
Our supporting services can also help businesses address gaps beyond SDR headcount. These include cold calling, cold email, LinkedIn outreach, pipeline generation, Data on Demand, conference lead generation and RevOps for HubSpot. For a company struggling with both prospecting capacity and CRM efficiency, that broader service portfolio may be relevant.
For New York teams, Whistle also highlights coverage across time zones, helping businesses coordinate outreach with their target markets. Before choosing a provider, it is still worth confirming the exact calling schedule, reporting cadence, meeting qualification criteria and division of responsibilities.
Ultimately, the decision comes down to your internal capabilities. If you need a provider to build and run your outbound sales development function, a managed programme may be the better fit. If you have the systems and leadership but need more SDR capacity, a placement model may be more appropriate.
If you're evaluating outsourced SDR services, book a call with Whistle and let’s discuss your ICP, existing sales setup and pipeline goals to determine which model best fits your requirements.
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