Sentence:  page 48: “Mondays would be great, especially after a weekend of <WSD>call</WSD>.” / page 56: “... I've got <WSD>call</WSD> tonight, and all weekend, but I'll be off tomorrow to help you some.” 
Meaning of the word marked with <WSD> tags:  A work shift which requires one to be available when requested (see on call).