OpenCall.ai vs Sierra AI Comparison (2025)
OpenCall.ai
Starting at $0.10/ minute
OpenCall doesn’t just pick up the phone and recite a script. It listens. It understands. And most impressively, it responds like a human would—fluidly, naturally, and with purpose. I’ve heard AI agents handle insurance verification calls, navigate complex scheduling workflows, and even wait patiently on hold before transferring the call back to a medical office at exactly the right moment. This isn’t voice automation; it’s delegation.
What makes OpenCall different is how deeply it integrates into a business’s backend systems. This means it can actually do things: check calendars, update patient records, confirm appointments, and triage urgent service requests—all without a human ever lifting the receiver. It’s not just about saving time (though it does, dramatically); it’s about transforming the customer experience into something responsive, seamless, and available 24/7.
What makes OpenCall different is how deeply it integrates into a business’s backend systems. This means it can actually do things: check calendars, update patient records, confirm appointments, and triage urgent service requests—all without a human ever lifting the receiver. It’s not just about saving time (though it does, dramatically); it’s about transforming the customer experience into something responsive, seamless, and available 24/7.
Key Metrics
Latency
700 ms
Automation
76%
Integrations
2000
Onboarding
2 days
OpenCall.ai
Score
93
Latency
700 ms
Automation
76%
Integrations
2000
Onboarding
2 days
Cost
Low
HIPAA Compliant
Yes
Sierra AI
Score
79
Latency
800 ms
Automation
60%
Integrations
30
Onboarding
7 days
Cost
Low
HIPAA Compliant
Yes
OpenCall.ai
OpenCall doesn’t just pick up the phone and recite a script. It listens. It understands. And most impressively, it responds like a human would—fluidly, naturally, and with purpose. I’ve heard AI agents handle insurance verification calls, navigate complex scheduling workflows, and even wait patiently on hold before transferring the call back to a medical office at exactly the right moment. This isn’t voice automation; it’s delegation.
What makes OpenCall different is how deeply it integrates into a business’s backend systems. This means it can actually do things: check calendars, update patient records, confirm appointments, and triage urgent service requests—all without a human ever lifting the receiver. It’s not just about saving time (though it does, dramatically); it’s about transforming the customer experience into something responsive, seamless, and available 24/7.
What makes OpenCall different is how deeply it integrates into a business’s backend systems. This means it can actually do things: check calendars, update patient records, confirm appointments, and triage urgent service requests—all without a human ever lifting the receiver. It’s not just about saving time (though it does, dramatically); it’s about transforming the customer experience into something responsive, seamless, and available 24/7.
Sierra AI
Sierra AI delivers a comprehensive conversational platform with multi-channel voice and chat, real-time analytics, and enterprise-grade security out of the box. But you won’t find a price list anywhere—expect to negotiate usage-based fees that climb steeply as you add advanced features or extra channels. Its “build once, run everywhere” Agent OS sounds neat, but customizing flows and integrating with legacy systems often requires dedicated engineering time. The command center offers deep controls, yet teams frequently find it overengineered for routine tasks and in need of training to manage. And despite claims of empathetic, human-like responses, at scale the agents can still stumble over accents or complex queries, leaving gaps that demand human intervention.
Full Comparison
| Vendor | Score | Latency | Automation | Integrations | Cost | Action |
|---|---|---|---|---|---|---|
OpenCall.ai $0.10/ minute | 93 | 700 ms | 76% | 2000 | Low | |
 Retell.ai $0.07 – 0.08 /min | 82 | 950 ms | 55% | 25 | Low | |
Sierra AI $2 per successful outcome | 79 | 800 ms | 60% | 30 | Low | |
 PolyAI $0.25 /min (example case study) | 67 | 1700 ms | 72% | 25 | Medium | |
 Bland AI $0.09/min | 66 | 1100 ms | 50% | 15 | Low | |
 Phonely $396 (yearly) | 61 | 1200 ms | 52% | 17 | Medium | |
 Hey Rosie $49/mo (250 min) + $0.25/min | 57 | 950 ms | 60% | 1 | Low | |
 Smith.ai $3.25 /call (Starter 30 calls @ $97.50/mo) | 55 | 2300 ms | 40% | 30 | Medium | |
 8x8 XCaaS $60 per seat per month | 49 | 250 ms | 50% | 15 | Medium | |
 CloudTalk $25 – $50 /user/mo | 47 | 23 ms | 40% | 500 | Low | |
 Synthflow AI $0.08 /min (Growth) | 20 | 2300 ms | 45% | 20 | Low | |
 Balto.ai $100 / seat /mo | 12 | 100 ms | 0% | 40 | High |