Incoming phone calls are not creating tickets in Zendesk

I haven't played with this for a while because it turned out to not be as useful as I hoped.  We don't have good records of phone numbers as much as email addresses here and many callers have multiple, different numbers they call us from.  Anyhow, I recall it was important to format the phone numbers in Zendesk correctly.  I'll test again and see if I can give you more specifics, but try things like 5105551212 or +15105551212, etc.

Brandon, 

Thank you for your response, it's really helpful. What do we do if it is a new customer with no phone number in the system?