"The six pages of White House switchboard logs for January 6, 2021, are complete based on an official review of White House records", according to a source familiar with the matter. There are no missing pages and the seven-hour gap is likely explained by use of White House landlines, White House cell phones and personal cell phones that do not go through the switchboard.
The missing calls also underscore something more endemic: the imperfect and antiquated system of tracking a president’s communications.
The White House call log is generated by a switchboard system that dates back to the 1960s, according to the National Archives. The version installed in 1963 was already considered “somewhat outdated” just two decades later.
And it’s certainly not one suited for the era of cell phones and text messages....
what is it about your own citation that you do not understand? maybe you can get some help with reading comprehension (as nd678 suggested).