There’s an old saying at Apache: “If it didn’t happen on the mailing list, it didn’t happen.”
At events and on teleconferences, people gather in real time, and some discussions occur in IRC or IM. However all information needs to be brought back to the appropriate list, and all decisions must be made on-list. When you hold a project call, discuss and deliberate, but bring all the information and recommendations from the call back to the project’s mailing list. Then allow other project committers - who might not have attended the call - sufficient time to read the recommendations and participate in any final project decisions.