One of the RegenCHOICE fields
A list of communication channels that the enquirer has shared with a particular contact.
The point here is that I may not want to share every communication channel up front with all contacts, as I may prefer them to go through one or more specific ones.
It could be arranged, for instance, that sharing communication channels is only mutual: that is, you see my phone numbers if and only if I see yours — and enforced symmetry.