When does it make sense to pay for discount points on a mortgage?

I am working on a feature story for the consumer Web site MagnifyMoney on when it makes sense for borrowers to pay for discount points to lower their interest rate when applying for a mortgage. With rates being as low as they are today, does paying for points make sense? If not, how high do rates have to rise to make paying for discount points a smart financial move? I’m interested in speaking with mortgage or financial professionals by phone about this topic. If you are available for a brief interview, please respond to this query.