Survey123 one field OR another must be filled in "Required"

[BradGeorgic]

I have 2 fields one called email and the other phone.  I want to make it so that either one of them have to be filled in for the survey to be sent.  How do I set the required and constraint fields?  Any help is appreciated

[NathanMack]

I have another way to go about this. I will provide screen shots of my actual survey, so I apologize for the funny field names. 

The first two rows are the questions I require one of two. I make the second relevant == 'no' if the first is answered. Third row, a calculate question checks if either of my first two questions are blank. Fifth row, combines all of the checks into a calculation that determines how many of the five question pairs was entered. Last is a read-only yes/no questions which is propagated by a calculation that looks at the concatenation previously created. In this case 1 or 0. I want all 1 (11111) for all five question pair being answered. The cell under required can be ignored in this example - It's related to something else going on in the XLS form. 
If the last question is not 'yes' it holds up the user, and they are unable to select 'yes' themselves. Their only option is to fill in sub_size or sub_class.
In the example @DougBrowning gave (tip of my cap, your idea inspired mine... go packers) my users would have to submit to realize they missed a data point. My survey is very large with 11 repeats. They input about 3,000 data points before submission. Users would have to go back through their repeats to find empty fields.

[DougBrowning]

Note you may see issues with a calc in a read only - yes field.  I have seen where 123 assumes the value cannot change since its read only.  I would go back and remove values and see if it still works.  Also test coming back from a draft and back from sent box.

Typically if the check is inside the repeat then it should fire before moving to the next one.  Hard to tell your use case.  Using emojis for instant checks may help also  https://community.esri.com/t5/arcgis-survey123-documents/how-to-simulate-instant-data-checking-using...