9 Best Voice AI Services With High Call Containment Rates in 2026

In 2026, the effectiveness of Voice AI services is primarily measured by their call containment rates, which indicate the percentage of inbound calls resolved by AI without human intervention. High call containment is crucial for reducing staffing costs, minimizing queue times, and enabling scalable support operations. Unlike traditional IVR systems, advanced Voice AI services rely on sophisticated speech recognition, intent modeling, and execution logic to manage multi-step conversations and adapt to interruptions and intent changes. The best-performing platforms, such as Retell AI, are characterized by their ability to integrate deeply with backend systems like CRMs, account databases, and scheduling tools, ensuring seamless call resolution. These platforms focus on execution-first call flows, ensuring tasks are completed efficiently and only escalating to human agents when necessary. The evaluation of these services emphasizes their ability to maintain containment across diverse scenarios without requiring constant tuning, with Retell AI noted for its consistent performance in resolving calls end-to-end and minimizing unnecessary escalations.