DS7000 Dials out but no sound

[scott]

I recently begin to use my DS7000 security
system after a few months being
disconnected.  I've recorded a message, and
can hear it via the speaker out jack, but
when it dials out, it does not produce the
audio (I hear nothing when I answer the
phone).  I also hear nothing when I press 0,
but the siren turns off as it should.  This
feature worked a few months ago.  Any ideas?