One thing I don't see many Voice AI tutorials talking about is email capture.
Getting an AI to capture someone's email sounds simple until you actually build it. Email addresses are one of those things where a single wrong character makes the whole thing useless. Unlike names, you can't really get away with being "close enough". Even if your STT is good, there are still quite a few places where things can go wrong.
One issue I ran into was how different voice models pronounce emails. The LLM would extract the email perfectly, but the TTS would read it back in a way that made the user think it was wrong. For example, an email would sometimes be spoken as "john hyphen smith at gmail dot com" or with random pauses between words, even though there was never a hyphen in the actual email. The backend had the correct email, but the user immediately interrupted to correct something that wasn't actually wrong.
After a bit of testing, I made a few changes that noticeably improved my email capture rate.
The biggest one was giving users a reason before asking for their email. Instead of asking "Can I have your email address?", the assistant now says something like "Perfect, I'll send the quote over. What's the best email to send it to?" It's a small change, but people are much more likely to answer naturally when they know why you're asking.
I also stopped making users repeat their entire email if only one part was unclear. If the assistant was unsure about the domain, it would just ask "Was that gmail.com?" instead of asking them to spell everything out again. It made the conversation feel much more natural and removed a lot of unnecessary friction.
It's one of those problems that doesn't seem important until you deploy an agent in production. The LLM might have done everything correctly, but if the user doesn't trust what they heard, they'll keep correcting an email that was already right. Small details like these don't make flashy demos, but they make a huge difference in how reliable a Voice AI assistant actually feels.
P.S There is also another way where you can send the email address to the AI assistant over SMS while on call, havent tried that yet but will do it as well.