I imagine each of the GMs have numbers for multiple team officials in each other team. My guess is they mostly correspond through email outside of busy days like deadline and the draft, or when there's a big name on the market. A guy like Treliving or Burke probably works from 6 am 8-10 pm during the season.
I don't think there's be that many wake up calls. For any deadlines, all the GMs would be up and working.
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