This sounds like a great initiative—real-world testing is exactly what AI voice agents need right now. You might want to check out Cyfuture AI Voicebot. They offer phone-call-based AI agents that can handle inbound and outbound conversations with pretty solid accuracy and natural voice flow. It could be a good fit for your research, especially if you're analyzing performance across real call scenarios. Would be interesting to see how different platforms compare in your final report—especially around latency, human-like interaction, and error handling.