Content Writer for Whistle with multidisciplinary experience spanning over a decade.
Cold calling is experiencing a strategic revival. As inboxes get noisier and digital channels reach saturation, more companies are turning back to voice. But today, the cold call is no longer a brute-force tactic. It’s a specialized skill, and one that many in-house teams lack the time, tools, or focus to execute well.
That’s why high-growth companies are increasingly turning to expert cold-calling agencies to scale smarter and faster. These partners bring proven playbooks, trained SDRs, and tech-enabled workflows that drive real conversations, not just dials.
If you’re evaluating B2B cold calling services in 2025, G2 and Clutch remain two of the most trusted review platforms for identifying top-tier providers. We’ve scanned both to highlight five cold calling agencies that consistently stand out for performance, transparency, and client outcomes.
Martal Group has carved out a niche in the outsourced sales development space, specifically targeting B2B tech and SaaS companies that need sophisticated, research-driven outbound campaigns.
They offer outsourced sales development for B2B tech and SaaS companies. Their services include appointment setting, outbound prospecting, and account-based targeting.
Their outbound prospecting methodology combines traditional cold calling with modern sales intelligence tools. SDRs are trained to identify buying signals, understand complex software ecosystems, and articulate technical solutions intelligently during initial conversations. This approach resonates particularly well with enterprise software buyers, who expect consultative interactions rather than generic pitches.
Martal operates on a monthly retainer model starting around $5,000/month, with custom pricing based on region and lead volume. This pricing reflects their positioning as a premium service provider, but clients often find the investment justified by the quality of leads generated.
Clients on Clutch and G2 highlight Martal’s responsiveness, reporting clarity, and the quality of meetings booked. It’s especially well-reviewed by mid-market and enterprise software firms who appreciate the strategic thinking behind campaign design. Many reviews emphasize that Martal’s SDRs feel like true extensions of internal teams, not external vendors.
Belkins provides comprehensive B2B lead generation through their multi-channel approach, combining precision research with strategic email campaigns and targeted cold calling.
They provide lead research, cold email campaigns, and SDR-as-a-service with a multi-channel approach that extends beyond traditional cold calling. While they emphasize email as their primary channel, their offering includes strategic phone outreach and LinkedIn prospecting to create cohesive buyer journeys.
Packages start at roughly $4,000/month, depending on the number of leads and services included. Custom sales development campaigns can increase that baseline, with pricing adjustments based on campaign complexity, target market requirements, and desired outcomes.
Belkins is praised for its research accuracy and email deliverability, critical factors in today’s increasingly sophisticated spam-filtering environment. On G2, users note the quality of appointments and strategic support from their account managers. The account management team provides ongoing campaign optimization, A/B testing insights, and strategic recommendations based on performance data.
SalesRoads focuses exclusively on U.S.-based cold calling services, positioning themselves as the premium choice for companies that prioritize domestic market expertise and cultural alignment.
SalesRoads’ core offering includes SDR outsourcing, campaign strategy, appointment setting, and real-time CRM integration that creates seamless workflows between external SDRs and internal sales teams. Their experts work with client teams to develop targeted messaging, identify optimal calling windows, and create follow-up sequences that maximize conversion opportunities. This strategic foundation ensures that cold calling efforts align with broader sales and marketing objectives.
SalesRoads typically prices based on dedicated SDR hours, starting around $8,000/month. Campaigns are tailored based on complexity and number of calls required, with pricing that reflects their premium positioning and U.S.-based talent pool.
One of the highest-rated cold calling agencies on G2, SalesRoads earns praise for its training quality, SDR professionalism, and strong communication cadence. The training program emphasizes consultative selling skills, objection handling, and industry-specific knowledge that enables meaningful business conversations.
While known primarily for virtual receptionists, Smith.ai also offers cold outreach services including outbound calling, lead qualification, and follow-up for inbound leads. This unique positioning allows them to handle both proactive prospecting and responsive lead management within a single platform.
Their outbound calling service combines traditional cold calling with intelligent lead qualification protocols. SDRs are trained to quickly identify genuine buying interest versus casual inquiries, ensuring that only high-quality prospects advance to sales teams. This filtering process saves internal resources while maintaining lead quality standards.
Pricing starts at around $300/month for basic receptionist services, with outbound calling packages starting closer to $1,200/month. Plans are modular and scale based on volume, making Smith.ai accessible to smaller companies that need professional outbound support without enterprise-level investments.
Reviews:
On Clutch and G2, users highlight fast ramp time, solid call scripts, and the ability to handle warm and cold leads alike. The fast ramp time proves especially valuable for companies that need immediate results or have seasonal campaigns with tight timelines.
Smith.ai is a solid choice for SMBs looking for affordable cold calling services to support internal teams.
Whistle is a global sales development agency that helps B2B companies scale pipeline with precision.
Whistle’s SDR services include cold calling, email outreach, LinkedIn prospecting, fully managed multi-channel outreach, and appointment setting. Their team becomes an extension of yours, ensuring a seamless handover of qualified leads from the SDRs to your AEs. With Whistle’s fully managed sales development service, you’ll have access to their world-class tech stack, proven processes, vetted SDRs, in-depth reporting and can start booking meetings in as little as 10 days.
Whistle offers flexible contracts and a variety of pricing structures. Packages typically start from around $1000/month depending on the service selected. All services include additional performance-based bonuses.
Clients consistently praise Whistle’s proactive communication, fast ramp-up, and focus on meeting quality. Their best in class teams and proven processes stand out on both Clutch and G2. Whistle is a preferred choice for tech startups and B2B companies of all sizes seeking measurable ROI from their lead generation efforts.
Explore Whistle’s SDR solutions
Partnering with a cold calling agency can accelerate your outbound motion—but only if it aligns with your business model and sales goals. From specialized U.S.-based teams to full-service outbound platforms, the best cold calling agency for you depends on:
Each agency on this list brings different strengths to the table. The right partner will act as an extension of your brand, not just a vendor dialing on your behalf.
Need help designing an outbound strategy or evaluating SDR partners? Whistle works with high-growth startups and B2B companies to build scalable, performance-driven outbound systems.
Speak with Whistle’s team to explore how cold calling can unlock your next stage of pipeline growth.
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