Hello @simonunivonix,
Thanks for your patience so far!
There is no such simultaneous Calling ring setting for Webex Calling Users through /users API.
This one is actually valid for a Calling Device or, Calling Workspace Phones, but in case for a Webex Calling User account - such feature is not available through API.
Hope this helps!
Please let us know for any further assistance.
Regards!
Sandip