There are several different ways companies provide consulting services. Primaraly, on-shore and off-shore.

On-Shore - people work for the client who reside locally to the region or brought from another reagion within USA.
Off-Shore - people work remotely from location other than USA.

Often times, both methods of consulting services are combined and people from off-shore are brought in to work locally on the project at the client site or dev. centers.

There are several major players in the field of providing consulting services to other companies. They are

1. Accenture
2. HP
3. IBM

These companies are major players and usually get 80% of all consulting business that is being generated within USA.