Serial number cross check to reference number.

Folks,
I'm in the market for a Ti Planet Ocean 232.90.42.21.03.001. A nice unit has caught my eye.
Pics look good. The serial number on the case, movement and cards all match.
I understand it is possible to cross check the serial number to the reference number.
Is there a website where this is possible, or should I ring my friendly OB?
Many thanks