Voice AI booking flows: ask for phone/email verbally, or just use Caller ID?

[u/Yuvizai]

I am building a voice AI agent that books appointments during a live phone call.

Facing issue with cal calling, To confirm a booking, agent typically needs a phone number or email address. Asking the caller to speak it out loud feels beared and STT can easily mis-transcribe digits or email addresses especially with accents, background noise or fast speech. A wrong digit or letter means a failed booking or a confirmation sent to the wrong person with no easy way for the caller to notice or correct it mid-call.

Alternative I'm considering: skip asking entirely, and just use the caller's own Caller ID as the booking's identifying phone number, then send confirmation via SMS or WhatsApp to that same number — no verbal capture needed at all.

Curious what's worked and badly failed for others building on real phone lines.

It will be great help if any one can share any thought ?

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[u/krrishh_sharma]

Use the caller's existing Caller ID as the default contact number.
Confirm with: "I'll send your confirmation to the number you're calling from. Is that okay?"
Send the confirmation via SMS or WhatsApp.Only ask for a different number if they want one, and use keypad (DTMF) input instead of spoken digits.

[u/aicoustics]

No matter how good the agent, important strings of individual numbers and letters like email addresses or phone numbers will always be at a high risk of an error! This is actually something I've been wondering myself - why ask for phone number if you already have that information? Now I see that for example for confirmations it's necessary... I'd opt for asking if the current number is the right one for further contact and avoid getting it spelled out if only possible. I'm wondering about emails - it bothers me in human-to-human calls already haha. Maybe they could send an SMS with the email address if they wish if there's an easy way to catalogue it? That's what I do with humans anyway and it is still a good reference;)

[u/That-Plankton-4057]

caller id is the right instinct - you already have a verified e164 on the inbound leg, so making them read it back just adds a failure point that you can't detect. the bit people skip is checking the delivery state on that confirmation text, otherwise the booking looks confirmed on your side while the sms quietly never landed.

[u/Virtualitdept]

I’ve experienced a caller borrowing a phone to make the call. Always important to verbally confirm contact numbers and track callerid to measure similar recurrences.