I'm not really accusing Bertram.
I'm just adding some information for people who wants to know about the call.

We have a real clue :
 Bertram is on the phone with someone and it's 12:37, the exact time Patrick Jane send everyone the text about the meeting.

Which definitively excludes theses guys :
Patrick Jane
Teresa Lisbon
Raymond Haffner
Bret Stiles
Reede Smith
Thomas McAllister

Since everybody wants to find out who is this guy, I will tell you. According to my psychic power, I'd bet the first name is Kevin, Chief of Sacramento Police District, and maybe Bertram was asking him to restrain his force if something unusual would happen.