I'm pretty sure it's just a normal old-school Securom disc check here.
After installing the game (some few weeks ago), the game did NOT ask for a serial code after the first boot-up - the manual doesn't even provide one here. Also, it did NOT even take any time to show the typical trying to "phone home" splash screen like most Securom Internet based DRM games do.
Only thing it cries for when I boot the game - whether I'm online or offline - is the disc, if it's not in the drive.
If you really want to be sure on this matter - if you have another PC, you might want to completely turn off your Net Connection entirely on that PC, install the game on that PC, try to boot the game, and see if it actually boots. If it does boot offline w/ the disc in the drive - there's no phone home process involved here.
EDIT:
A lot of Securom talk in this threa...the terms of the DRM are buried here...?