In chapter 4, note down the spybuy number on the television inside the spy control centre room (where the glass elevator is). The TV is in the unchanged room (the lever position to up).
Then, make note of Ruby's account number in her office.
Keep these notes.
In chapter 5, ON THE SAME SAVE FILE, you can ring Spybuy in her study, and order the shoephone (option 2 on the phone). Go to the postbox to receive the item and this achievement.