Her job is specific to answering phone calls.
The sentence above seems a bit awkward to me. What is meant here is that her job is to answer phone calls; that's her only responsibility.
But it's difficult to explain why we'd better avoid "specific" in this context since dictionaries give the following definitions:
- specific (to): limited to one particular thing (Macmillan Dictionary)
- something that is specific to a particular thing is connected with that thing only (Collins dictionary)
After all, would you say "specific to" can be used in the sentence above? If not, why?