I would ignore the calls but that's just me. Maybe Starsky has some better advice but I would ignore and if she texts just say.. Something along the lines of hey sorry I was in the middle of something.
Well, of course the REAL key here is to mostly really BE in the middle of something! You know, cuz you're busy, GALing, and The Most Interesting Man in the World . . . right?
But yeah, unless and until you are, then FAKE IT. I agree with everything T wrote right there^^^. Healthy boundaries are KEY in these situations, and good for BOTH of you if you think about it.