5 Best Callbox Alternatives for B2B Growth in 2026

Telemarketing Professionals: The Local-Caller Specialist

Telemarketing Professionals is an Australian-owned business founded in 2010, and its own site is explicit that it employs only local Australian callers “with an easily understood neutral accent,” a direct contrast to the offshore call-centre model some buyers associate with outsourced telemarketing. Services extend beyond appointment setting into call centre work, event and seminar booking, research calls, and database cleansing.

Neither a founding-year-verified review count nor published pricing appears on their site; the reviews visible are Google reviews collected through Trustindex, not an independent platform like Clutch or G2. That's a real evidence gap next to Belkins or LevelUp Leads, not a mark against service quality.

Local calling capacity solves a different problem than knowing which contacts to call first; the buying signals worth monitoring before a call happens are a separate question entirely.

Choose Telemarketing Professionals if the requirement is specifically an all-Australian calling team and you're comfortable evaluating fit through direct conversation rather than a large third-party review trail.

Belkins: The Premium, Heavily-Reviewed Option

Belkins is a Delaware-headquartered agency founded in 2017 that has grown to 200+ employees serving 1,000+ clients, with named clients including GE Healthcare and Cisco. It holds 223+ reviews on Clutch, among the largest review footprints in the appointment-setting category, and reports metrics like 10:1 average ROI and over 200,000 appointments scheduled across its client base.

That evidence trail comes at a price. Belkins doesn't publish pricing, but third-party benchmarks and client-reported figures put most engagements between $5,000 and $25,000 a month, and it operates on a best-effort model rather than a contractual guarantee of meeting volume; some reviewers note this as a real limitation when results run below expectation.

Choose Belkins if you want the largest verifiable review trail on this list and can support a $5,000+ monthly retainer without a results guarantee attached.

LevelUp Leads: The Lower-Cost Outsourced SDR

LevelUp Leads is a founder-led, US-based outsourced SDR agency with 56 reviews on Clutch and pricing that starts near $5,000 a month, or $4,000 to $49,000 per project depending on scope. It publishes three explicit service tiers, Fractional SDR, Full-Service SDR, and Growth, which is more pricing structure than most agencies in this category disclose.

The trade-off shows up in ramp time and process: most clients report a 90-day ramp period before results stabilise, reflecting LevelUp's largely manual prospecting and research workflow rather than an automated enrichment pipeline.

Choose LevelUp Leads if budget is the primary constraint and you want a named, tiered price to plan against rather than a quote-based conversation.

Apollo: The Self-Serve Software Option

Apollo is not an outsourced agency, it's sales intelligence and engagement software built by ZenLeads Inc., founded 2015 in San Francisco. It combines a 230-million-contact database with email sequencing, a built-in dialer, and CRM sync, priced per seat from a free tier up to $119 a month on its Organization plan, and serves roughly 100,000 paying companies.

Choosing Apollo means choosing to run outreach with your own team rather than handing it to an outsourced provider, which is a different decision than picking between Callbox, Belkins, LevelUp Leads or Telemarketing Professionals. The credit-based pricing model can also produce costs beyond the advertised seat price if a team exceeds its email, mobile, or export allowance.

Choose Apollo if the actual gap is tooling for a team that already has people to run outbound, not outsourced calling capacity.

Intelligent Resourcing: The Different Category Entirely

Intelligent Resourcing isn't competing with the other four on outreach volume or seat price, because it doesn't sell outreach at all. It's a build: signal detection, enrichment and routing logic configured on the client's own CRM, typically over 4 to 6 weeks from ICP finalisation.

That timeline is the real trade-off against this list. Telemarketing Professionals, Belkins and LevelUp Leads can all have calls happening within days to a couple of weeks. Apollo is live the moment a seat is purchased. Intelligent Resourcing asks for weeks of setup before the first outreach goes out, in exchange for a system rather than a subscription or a rented team, the specific mechanics of which are covered in the full Callbox comparison.

Choose Intelligent Resourcing if you can absorb a multi-week build before outreach starts, and what you actually need solved is timing and routing, not raw calling or emailing capacity.

How to Choose Between Them

The five options split into three genuinely different jobs, not five versions of the same job. That distinction is the starting point of GTM Engineering as a discipline: match the tool to the actual constraint, not the category label.

• Need Australian-accent calling specifically: Telemarketing Professionals
• Need the largest review trail and can pay for it: Belkins
• Need a named, lower price point: LevelUp Leads
• Already have people, need the tooling: Apollo
• Can absorb a multi-week build for a system instead of instant capacity: Intelligent Resourcing

Ready to figure out which gap you actually have? Talk to the lead generation team before committing to a retainer.