In a note to clients — as reported by “AllThingsD” (http://allthingsd.com) — J.P. Morgan analyst Mark Moskowitz thinks Apple will make 20 million so-called iPhone 5 units in the September quarter, and an additional 39 million in the December quarter.

If so, Apple will meet or beat J.P. Morgan’s total iPhone unit estimates of 39.4 million for the December 2012 quarter and 37.8 million units for the March 2013 quarter. Moskowitz estimates that iPhone 5 units could be 50% to 60% of total Apple phone shipments “in the first two quarters of volume ramp, scaling up after that.”