ASHISH
Yes, it is Sub-contracting.
In this discussion of yours you'd get only that information which is already available on net, which you could also have found with ease. However please refer to following useful links:
External Refurbishment process for Repairable Spares with Serial number integration
Without Subcontracting how to handle external jobs
Refurbishment vs Subcontracting
External Refurbishment Process
...and many more available depending upon your search skills.
If you confine to the present discussion you will be getting only that much which the present active experts have. But through Google searches you will be getting all discussions over a decade.
Also you should make it a point to close a thread opened by you if the discussion completes OR after a reasonabe wait.Please review and close several of your such open threads by visiting your own Stuff here
Good luck
KJogeswaraRao