But by extrapolating from previous quarters and reading between the lines, we can make some rough estimates. Here are the data points as we understand them:

How many new iPhones did AT&T sell?

AT&T’s (T) widely leaked “best-ever sales day” memo ticking off the records set on June 19, 2009 — the day it began selling the iPhone 3GS — is packed with superlatives but notably lacking in numbers. (See memo below.)

Unlike Apple (AAPL), which reports on a quarterly basis how many iPhones it has shipped, AT&T keeps its unit sales figures close to its chest.

The new memo trumpets the fact that iPhone sales on June 19 “exceeded sales recorded on 2008’s iPhone launch day,” without saying how many phones it sold on either day.

But by extrapolating from previous quarters and reading between the lines, we can make some rough estimates. Here are the data points as we understand them: