When any company outsource their work to some other company then they usually keeps two types of team: Offshore and Onshore/Onsite. People who works at clients end under clinets netwrok comes under Onshore team and the other team is known as offshore. Basically Onshore people do all the requirement gathering of the client and does development work as well if required by the client. All offshore people get involved in many different activities such as development, providing support and many other things. Onshore coordinator informs the offshore team about any changes in the work and interacts with offshore team for the requirement.
Onshore and Offshore model means, some people will be sitting at Customer location to gather the requirements, and provide the solution and actual development/build will happen at Offshore..
That means entire project team will be split into 2 .. So responsibility in Onshore is to provide the proper requirements, and to coordinate the offshore team.. And offshore team have very limited access to customers..
This will help to cut down costs,geography difference and it is more towards operations point of view.. it depends on the customer to customer and vendor to vendor.