I was reading a grammar book called Essential Grammar in Use. As for the usage of "Will" it gives the examples bellow:
Sue travels a lot. Today she is in Madrid. Tomorrow she'll be in Rome. Next week she'll be in Tokyo.
You can phone me this evening. I'll be at home.
Leave the old bread in the garden. The birds will eat it.
We'll probably go out this evening.
Will you be at home this evening?
I won't be here tomorrow.
Don't drink coffee before you go to bed. You won't sleep.
I read on many websites that when we use will for future decisions, it means that our decision is made at the time of speaking. Now, my question is, in this example "You can phone me this evening. I'll be at home.", is 'being at home' is a decision the speaker made? If so, could it be one made at the time of speaking?