Best is to look if dialpad have webhook for this kind of event

If not, I think you may need to split your process in two parts:
A) Create new users. Use the API call that get the list of users and use Schedule API Workflow on a list. If the item exist, you can update it (if needed) and if not, create a new one
B) Schedule an API workflow on a list of user from your DB and there’s probably an API endpoint to get this specific user (with dialpad user ID). If this return something, that’s fine, if not, delete thing. (Don’t forget to activate continue if error checkbox in API Connector)

Another solution could be to use the First API call, get the list of USER ID and use minus list like API call ID:minus list Do a search for user’s each item dialpidID (Create new user for each item that remain and update all item with a field like a date for last “validation” date. Delete everything that remain after that was not updated “today”. This option will probably take less WU.

There’s a lot of possible way to achieve this. But the best is to first look for webhooks.