Modem-on-Hold functionality

Hi, I am in the process of converting my mother to use Linux instead of
Windows.  So far so good, except for one thing--she lives in the country
and relies on dial-up, so she uses one of those MOH programs for windows
like Internet Call Manager to let her know if someone is calling her.

I see that the Linuxant FAQ says that support for v.92 and MOH is in the
driver but it is lacking a GUI app.  Is Linuxant still planning to write
this app?  If not, is the interface to the MOH functions public, such
that I could write the GUI app?  If so, is there any documentation about
the interface available?  I haven't checked the source much yet, as I'm
just wondering at this stage if it's possible.

Thanks,
Mark Cote