forms - Common pattern for "multiple fields, at least one required"

Clearly the asterisk is a popular web standard for identifying unconditionally required fields.

But what if any one field out of several is required? For example, there are separate fields for home phone, work phone, and cell phone. At least one phone number of any kind is required.

Do people usually just indicate this using in-page instructions? Instructions aren't very elegant, but it seems like asterisk variations (hatchet, cross, etc) usually just confuse people. Is there a better solution?

Answer

I'm not aware of a conventional better solution. In situations like these I try to do something like this, with visual grouping of the alternative fields and placing the asterisk next to the group title:

Sometimes it works, sometimes - not so much.

Also, it's always a good idea to use inline validation, but it's doubly helpful here.