My apologies to all for not having kept up with this thread.
At Checkered Flag, with which I am no longer affiliated, the Service Customer Care Center, plus two off-site (out of the call center) operators, answered all inbound calls to the organization - in 2009 alone, the volume was staggering. With "right-sizing" throughout the organization, there would be no way for service advisors to adequately handle the volume of calls they received. Thus, the BDC.
As to upselling, yes, the service coordinators were responsible for upselling. But, not in the same sense as the advisor. It's one thing to suggest additional services based on mileage, over the phone, and another to upsell repairs and maintenance while you're "touching" the vehicle. This affords a service department two opportunities to upsell two groups of services/repairs.
Service advisors MUST stay in constant contact with customers - while the vehicle is in for service. In most other cases, it's more appropriate to have the BDC serve as the telephone interface with the customer.