AI Voice Platform Comparison for Small Business Use Cases

We provide AI voice agent consultation and solutions in Upwork. One of clients’ frequent questions is which platform is best/perfect for their use cases, like lead qualification, AI receptionist, customer support, etc.

This post provides our thoughts on this question. Our overall feeling is that the AI agent technology is still not there yet. It seems close but there are many corner cases the AI bot doesn't handle well.

Four major players in the AI voice platforms:

1. Bland ($65M funding)
2. Retell ($4.6M funding)
3. Synthflow ($7.4M funding)
4. VAPI ($20M funding)

We will only talk about Bland, Retell and VAPI. We firstly tried Synthflow and found the UI was buggy (the prompt editor froze for 20 seconds to 30 seconds when we were editing the prompt). Currently we don't use it anymore.

Recommended use cases based on Upwork jobs we delivered:

1. Bland. We recommend Bland for lead qualification as the lead qualification has a strict conversation flow (like asking questions, extracting variables, and making webhook calls). Clients/contractors can draw flow diagrams to build AI voice agents. We also find Bland is not a good fit for a small business with a monthly budget less than 5K. The reason is that common tools (like warm transfer, SMS sending) for AI voice agents are only available to enterprise clients. But warm transfers are critical for small businesses.
2. Retell. We recommend Retell for customer support in contact centers. Retell has the best voice among competitors. One use case we build in Retell is the live translator in the ambulance call center. We tried the same prompt with the same LLM setup in VAPI. We found Retell performs way better than VAPI in terms of the translation quality and reliability. Another common scenario in the customer support domain is to have 3-way merge so that the agent can tell the summary to the transfer number while the caller can hear the conversation.
3. VAPI. We recommend VAPI for AI receptionists and phone answering use cases. We can write a prompt and ask LLM to do the magic if callers ask questions not included in the prompt. We can set up custom tools to trigger automation (like update CRM) and warm transfer to connect to the stakeholders. One feeling we have is that VAPI is way more complicated than the other two platforms. If you don’t have developer experience and have a budget to hire a contractor, it is better to try Retell as Retell has many integrations.

If you have any other questions or we miss anything, feel free to comment. We like to explore AI voice agent space together.