How to create field collection from existing fields?

Could there be an easy way to create a field collection from existing fields?

For example, I have an addressfield field and a separate phone field but I now realize that each phone number is 1-1 to an office location (the addressfield) and it would make sense to put this information into a field collection. Then, I can make the field collection unlimited, rather than making each of the independent fields unlimited.

In the easiest case where, previously, there was only one instance of each of the fields going into the field collection, is there an easy solution to creating the field collection from the existing fields?

Thanks.