[Asterisk-Users] Music on hold not initiating RTP stream?

[Ray Van Dolson]

I've been having problems getting MusicOnHold to work, so I've dumbed down my
setup to as simple of a setup as I can.

Asterisk 1.0.9.  SIP ATA's (Sipura SPA-2002's)

<SIP ATA 1> <---> <Asterisk> <---> <SIP ATA 2>

Both ATA's have public IP's.  No NAT'ing going on here.  Reinvites are allowed
so the media stream bypases Asterisk once a call is established.

The ATA's are Sipura SPA-2002's and I have MOH Server set to 899 on each.

In Asterisk I have the following extension defined.

  exten => 899,1,Answer
  exten => 899,2,NoOp,${EXTEN}
  exten => 899,3,NoOp,${RDNIS}
  exten => 899,4,MusicOnHold(random)
  exten => 899,5,Hangup

If I dial extension 899 directly, I hear the music I've chosen as expected.
This tells me that mpg123 is not the problem ;)

However, with a call in progress, if I hit hold or flash on SIP ATA 1, it
behaves correctly, but no music on hold is heard on SIP ATA 2.  I can see in
my Asterisk console that MusicOnHold() gets called and tcpdump shows the
INVITE that first sets the RTP source to 0.0.0.0 then sets it to the IP of my
Asterisk box.

However, no RTP stream initiates, thus no music on hold is played.

I'm going to dig into the RFC a little to see how this is supposed to work,
but any ideas from what I've described?  I know others are doing this without
any problems.

Oh yeah, and my musiconhold.conf file:

random => quietmp3:/var/lib/asterisk/mohmp3,-z

Thanks in advance.

Ray