Vendor 1
FonosterAI Voice Agents
Open-source voice and AI telephony infrastructure for building programmable voice agents and SIP applications.
Usage-basedPriceNo reviewsRating2020Founded
Fonoster vs Retell
Vendor decision canvas
Vendor 2
RetellAI Voice Agents
Voice AI API for building production phone call agents with low latency.
No reviewsRating2023Founded
Carry this decision forward
Fonoster + Retell can move into a shared evaluation.
Evidence sheet
2-vendor view| Vendor 1 Fonoster AI Voice Agents The open source alternative to Twilio | Vendor 2 Retell AI Voice Agents AI Voice Agent Platform for Phone Call Automation | |
|---|---|---|
| Overview | ||
| Category | AI Voice Agents | AI Voice Agents |
| What it is | Open-source voice and AI telephony infrastructure for building programmable voice agents and SIP applications. | Voice AI API for building production phone call agents with low latency. |
| Pricing | ||
| Price | Usage-based | — |
| Pricing model | Tiered plans | Usage-based |
| Free options | Free plan, Free trial | Free plan, Free trial |
| Company | ||
| Founded | 2020 | 2023 |
| Team size | 11-50 employees | 11-50 employees |
| Headquarters | San Francisco, CA | San Francisco, CA |
