I believe it sends to various models in the background, So largely a harness / framework. Ibm does have its own model which is one of the options for Bob to use.
(Note, I'm an IBMer but nowhere near this so my comment is strictly from my public knowledge/awareness:).
Never heard of Granite? https://huggingface.co/ibm-granite
(I'm also an IBMer.)
so it routes to actual AI companies and IBM adds additional cost on top. what a business model.
and hides from you what models it's actually using