I have similar issue like yours, I reached to to see if even zoom contact center can solve this but no i dont think it is available.
I have a couple question for you.
from what i understand, when user click zoomphonecall , you create a record somewhere and wait until the user click Dial, then you match the webhook with that record?
If so. what if the user waited 5 - 10 minutes to call instead of calling immediately, do you invalidate the initial record within a time frame?
for the record, I have each user with their own phone numbers, the outbound callee is one phone number, i’m trying to distinguish which profile they are calling for.