I told my work I was happy for them to call/text if there were any questions (eg couldn't find a file, unsure of history of something, etc) but I didn't want to do any actual work. They called a few times before bub was born and I was happy to assist as the two minutes of my time on the phone saved them hours of searching. (Maybe my handover wasn't great!!!). They called once after bub was born and I was actually more than happy to chat as DF was overseas and I was starved of non-baby related conversation 😜.
If I was you I'd probably call your boss back and see what he wants. If is something that two minutes on the phone can resolve then fine but if he asks for you to do a few hours of work then say no.