Changing user MFA Type from SMS to Voice by API

Is it possible to change a users prefered mfa Type from SMS to voice by API?

Or ist this just possible by deleting the users mfa setting an letting him reenter his mobile number and selecting the prefered transport type during the onboarding?

On the Security info page, select Change next to the Default sign-in method information.

As far as I understand your solution, this will change the setting for ALL users. That’s not what we want. Currently the following setting is activated and should stay activated:

Phone Message
Users will receive a text message or voice call containing a verification code.

The only thing we want to change is if user XYZ has choosen SMS at first time and calls our support we want to change the MFA transport Type for user XYZ from SMS to Voice. And this by API if possible.
Is there any method which can handle this?