You can ask for them to provide "extra detail" over email outside of the call as you think that question may need some detailed thought/extra checks etc.
I will typically follow up a phone call with something like "Hi Percival, just to follow up on our phone call today, we landed on Widget A going into V1.2.34 instead of 1.2.32, having the Howitzer firm handle the BigDoodle transition to Python instead of doing it ourselves, and you said that you'd follow up with the FlimFlams and I'll follow up with the Wannabes and the Charlitans. Let me know if I missed anything."
Doing this has saved my butt more times than I can count.