OK, I checked the manual for the Microsoft BASIC Interpreter (1984, green, has a picture of a 128k Mac on cover) and it does allow ToolBox access, but only to graphics routines. There is in-built support for networking, but it's only standard serial communications, not AppleTalk specific.
Later versions of MS BASIC may have had AppleTalk support, but I don't have the manuals for those later ones.
I also have the manual for Microsoft QuickBASic for Mac, which is a newer version. I will take a look at it later. I'm not sure if it's conveniently located or not.