Dell XPS 10 Tablet - Manual (Page 39)

Locating Your Service Tag and
Express Service Code
If you are still unable to resolve the problems or require any additional
help on your tablet, you may contact DELL for additional technical
assistance.
NOTE: Before you call, have your Express Service Code ready. The code
helps Dell’s automated-support telephone system direct your call more
efficiently. You may also be asked for your Service Tag.
The Service Tag and Express Service Code for your tablet can be found
on a label at the bottom right of the tablet back cover.
Locating Your Service Tag and Express Service Code 39