We tested the top AI voice calling platforms using real phones, real networks, and real-world conditions. No demos, no marketing fluff, just production data from May 2025. Here's what agencies actually need to know before choosing their AI voice infrastructure.
If you prefer a visual representation here is a quick comparison chart.
The contenders and testing methodology
Trillet, Bland AI, Retell AI, and Vapi represent the current market leaders for AI voice calling. We tested each using GPT-4o equivalent models on actual phone calls within the United States, measuring latency, features, and the total cost of running agency operations at scale.
Every platform claims sub-second latency. Reality proved different, but not necessarily worse. The 2-3 second response times we measured still enable natural conversations, just not the sci-fi instant responses marketing teams promise.
Performance metrics that matter
Latency results surprised us. Trillet and Retell tied at 2.1 seconds, Bland posted 2.4 seconds, and Vapi trailed at 2.6 seconds. That half-second spread might seem negligible, but it impacts conversation flow and completion rates.
Pricing varies significantly. Trillet and Bland both charge 9 cents per minute. Retell costs 12 cents, a 33% premium. Vapi leads at 15 cents per minute. For an agency running 50,000 minutes monthly, that's a $1,500 difference between the cheapest and most expensive options.
Concurrency starts at 10-20 simultaneous calls depending on platform, with all offering upgrades for higher volumes. This becomes a simple math problem: more concurrent calls equals more clients served simultaneously.
The feature matrix reveals platform priorities
Some features sound boring until you need them. Call memory, the ability to reference previous conversations, exists in Trillet and Bland but not Retell or Vapi. Imagine your AI calling the same prospect twice and having no recollection of the first conversation.
Dynamic webhook tokens enable secure CRM integrations without hardcoding credentials. Trillet and Bland support them; Retell and Vapi don't. This matters when managing multiple client integrations.
Auto callback functionality lives exclusively in Trillet. When prospects request callbacks, Trillet's AI actually delivers them. The other platforms require manual scheduling or custom development.
Honeypot detection represents Trillet's most unique feature. These trap numbers designed to waste AI callers' time cost agencies thousands in burned credits. Trillet identifies and avoids them automatically.
White-label capabilities define agency readiness
Agencies need to present solutions as their own. The platforms take surprisingly different approaches.
Trillet offers native white-label at $500 monthly including $500 in credits, essentially break-even for active users. This includes dedicated Slack support with two-hour response times.
Bland focuses entirely on enterprise direct sales with no white-label options.
Retell and Vapi rely on third-party providers for white-label solutions, adding $200-500 monthly to platform costs. These work well but introduce additional vendor relationships to manage.
Support structures and hidden costs
Support quality varies dramatically. Trillet provides dedicated Slack channels for white-label customers. Bland reserves support for enterprise contracts, directing others to Discord. Retell and Vapi offer documentation and community forums, with third-party providers handling white-label support.
The math gets interesting at scale. An agency running 100,000 minutes monthly faces these costs:
Trillet: $9,000 (including white-label)
Bland: $9,000 (no white-label available)
Retell: $12,300 (including third-party white-label)
Vapi: $15,300 (including third-party white-label)
Platform philosophies and target markets
Each platform clearly targets different users. Bland builds for enterprises with development teams who can create missing features. Their enterprise-only support model and absent white-label capabilities confirm this focus.
Retell and Vapi provide powerful APIs expecting developers to build solutions on top. Their third-party ecosystems prove this strategy works, though it adds complexity for agencies wanting turnkey solutions.
Trillet appears designed specifically for agencies running outbound campaigns. Features like honeypot detection, auto-callback, and native white-label address common agency pain points directly.
Making the choice
The "best" platform depends entirely on your use case.
For agencies running outbound campaigns, Trillet's feature set aligns perfectly with common requirements. The native white-label and unique features like honeypot detection provide immediate value.
For enterprises with development resources, Bland offers solid infrastructure at competitive pricing. The lack of agency features won't matter when you're building internal tools.
For maximum flexibility, Retell provides a robust platform with an established ecosystem. The higher costs and third-party dependencies trade off against platform maturity.
For custom implementations, Vapi's API-first approach enables unique solutions. The premium pricing makes sense only for specialized use cases where customization matters more than cost.
The market evolution continues
The AI voice platform space remains remarkably dynamic. Established players like Retell and Vapi attracted significant venture funding, Vapi alone raised $25 million at a $130 million valuation. Bland secured $65 million in under ten months. This capital enables continued innovation but also locks in certain strategic decisions.
Meanwhile, newer entrants like Trillet can learn from others' mistakes. By studying what agencies actually struggle with, honeypot calls, callback management, white-label complexity, they've built targeted solutions rather than generic platforms.
The bottom line
For agencies starting their AI voice journey, the decision often comes down to build versus buy. Platforms like Retell and Vapi offer powerful tools for building custom solutions. Bland provides enterprise-grade infrastructure for internal use.
Trillet takes a different approach: providing a complete solution optimized for the most common agency use case, outbound calling and SDR operations. The included features eliminate development time, the native white-label preserves agency relationships, and the competitive pricing enables profitable scaling.
The market has room for all approaches. Enterprise clients need Bland's infrastructure. Developers want Vapi's flexibility. Agencies running outbound campaigns increasingly gravitate toward purpose-built solutions that work out of the box.
As AI voice technology matures, expect further specialization. The one-size-fits-all platform is giving way to targeted solutions for specific use cases. For agencies, that specialization might be exactly what they've been waiting for.
