Thanks to everyone for their responses. I've gotten more
information than I could have hoped for!!
This is being done on a client's computer, not my own, and I
don't have access to it at the moment. But my memory is half
decent on good days, so . . .
We are using the Google Voice plug-in, not Hangouts. On my own
computer I have the Voice plug-in under Firefox for one GV
number and the Hangouts App/extension under Chrome for another.
On the client's machine I believe it's Voice and Firefox.
I have already reported this issue as best I can to both
Freedom Scientific and Google. I am hoping that Google will
take the accessibility issue seriously and look into this.
In the meantime I think the work around we'll end up using is
having her Google Voice number ring her cell number on her
iPhone. I'll probably also try to assign some sort of dedicated
ringtone to those calls, but I've got to figure out the best way
to do that, so that she knows whether the call is coming in
directly to her actual cell number or being forwarded from GV.
It will probably not be until after the holidays that we next
get together and that I can do this, but her internship won't
start until that time, either. I try to avoid working "at
deadline" for precisely these reasons. Having done this sort of
work for some years now I have long ago been disabused of the
notion that JAWS, or any other assistive software, is likely
going to behave in the way I want it to, particularly with new
or obscure features. Given the pace of change in web browsers
and general web coding it's a miracle that the assistive
technology companies can keep up with it at all. I just wonder
how long it will be until stuff becomes stable with Windows 10!