asterisk users - Jun 2006 - Strange problem with MusicOnHold - works outgoing - works with extension - but not incoming!

I've got a strange situation with musiconhold.

It works if I dial my extension 6000:
>From extensions.conf:
exten => 6000,1,Answer
exten => 6000,2,MusicOnHold()


Debug output if I call 6000:
    -- Executing Answer("SIP/gs1-b6ee", "") in new stack
    -- Executing MusicOnHold("SIP/gs1-b6ee", "") in new
stack
    -- Started music on hold, class 'default', on SIP/gs1-b6ee
    -- Stopped music on hold on SIP/gs1-b6ee
server*CLI>


If I dial out and put a call on hold the other party hears the musiconhold:

Debug output when I do an outgoing call:
    -- Executing SetCallerID("SIP/gs1-cb7a",
""Anonymous" <0031xxxxxxxxx>")
in new stack
    -- Executing Dial("SIP/gs1-cb7a",
"SIP/0031xxxxxxxxx@voipbuster") in new
stack
    -- Called 0031xxxxxxxxx@voipbuster
    -- SIP/voipbuster-ac66 is making progress passing it to SIP/gs1-cb7a
    -- SIP/voipbuster-ac66 answered SIP/gs1-cb7a
    -- Attempting native bridge of SIP/gs1-cb7a and SIP/voipbuster-ac66
    -- Started music on hold, class 'default', on SIP/voipbuster-ac66
    -- Stopped music on hold on SIP/voipbuster-ac66


But.... If somebody rings me and I put him on hold he hears nothing:

Debug output for incoming call:
    -- Executing SetCallerID("SIP/gw02-mci.budgetphone.nl-42ba1908",
""prive" <xxxxxx>") in new stack
    -- Executing Dial("SIP/gw02-mci.budgetphone.nl-42ba1908",
"SIP/sipura&SIP/gs4") in new stack
    -- Called sipura
    -- Called gs4
    -- SIP/sipura-7685 is ringing
    -- SIP/gs4-4a86 is ringing
    -- SIP/gs4-4a86 answered SIP/gw02-mci.budgetphone.nl-42ba1908
    -- Attempting native bridge of SIP/gw02-mci.budgetphone.nl-42ba1908 and
SIP/gs4-4a86
    -- Started music on hold, class 'default', on
SIP/gw02-mci.budgetphone.nl-42ba1908

According to the logs it starts the music on hold, the same way as in the
other calls but it stays quiet! I've tried everything but I don't know
what
else to check.

I've got Asterisk 1.0.7-BRIstuffed-0.2.0-RC7k on a debian machine.

In my sip.conf:
[general]
musicclass=default
musiconhold=default

(I tried it with only miscclass, only musiconhold, and without both, nothing
changes)

In musiconhold.conf
[classes]
default => quietmp3:/usr/share/asterisk/mohmp3

What can be wrong, what else can I check?

Kind regards,

De Boer