which one a Technical Support or Help Desk

I am working for a new Small ISP and we are trying to establish a center for receiving technical calls and inquires from customers and the technicians in this center may do some basics troubleshooting. What is the suitable title for this center and what we should call this people who do this job? Technical Support, Helpdesk, or Call Center. does each term has a specific meaning? And is there any standard structure of this center? And what is the relation of this people with other network/software Engineers? Thanks in advance. -- Tarig Adam