[Asterisk-Users] GnoPhone/IAX: "No audio available" ?

[sirkus]

We have successfully set up * and can make calls and leave/check
voicemails... Except in one case.  I have set up Gnophone, and I've
configured it to use our new * server. I can make outgoing calls, and I
can navigate menus and check voice mail.  However, if I ever try to
leave a voicemail for another extension, I hear the greeting, but as
soon as the greeting is over there is a pause and it hangs up.  The *
logs show:

  == Parsing '/etc/asterisk/voicemail.conf': Found
    -- Playing 'vm-theperson'
    -- Playing 'digits/1'
    -- Playing 'digits/0'
    -- Playing 'digits/3'
    -- Playing 'vm-isunavail'
    -- Playing 'vm-intro'
    -- Playing 'beep'
    -- Recording to /var/spool/asterisk/vm/103/INBOX/msg0000
WARNING[1209214400]: File app_voicemail.c, Line 707 (leave_voicemail):
No audio available on IAX[sirkus at sirkus]/1??
    -- User hung up

It says the user hung up, but I (as the user) did not. Gnophone may
have, but it seems odd that I can do all the other functions (including
outgoing calls) but I can't leave a message.
Any ideas?

Thanks.