Is it mandatory to use "Email Address" field as unique identifier in "Imports" of OSC Integration?

Hi Team,

In our Eloqua instance, we have enabled "Contacts with no Email Address" feature, since the requirement is that the "Mobile Phone" should be the unique identifier. So, in the Oracle Sales Cloud Integartion app, where the "Imports" is created, can we use the "Mobile Phone" as the unique identifier instead of "Email address" field as shown above in the screenshot?

So, if we can use the "Mobile Phone" as the unique identifier, will the Import Integration of Oracle cloud fail? or are there any other consequences for the same?