How to integrate Twilio SMS and Zendesk identifying users correctly?

Hey there,

We use Twilio API to send SMS to our users, and when they respond to any of those SMS we want the message to be forwarded to Zendesk and added to a ticket, if there is no ticket it should create one otherwise update the existing one.

We are playing with Twilio webhooks contacting Zendesk API, but we have a few issues...

When an SMS comes in Twilio, it only contains a phone number (FROM) and the body of the message, but Zendesk API requires a name or email field in the "requester", so it is not able to identify the user by the phone number. All our users are currently in Zendesk and all users have a phone number, no duplicated phone number either.

Also, every new SMS that comes in Twilio and pings Zendesk API is creating a new ticket instead of updating the current one, is there an UPSERT way to handle tickets via the API to create or update those?