[Asterisk-Users] Starting RTP with Dial and MusicOnHold

[Aaron Clauson]

Hi,

I'm trying to get Asterisk working with a supplier's Cerpack switch and
everything is working except audio ringback for calls coming from Cerpack to
Asterisk.

The Cerpack switch only does out of band progress indication (seems a bit
strange for SIP to SIP calls?!) so I've spent the last two days trying to
find a way to force Asterisk to send an RTP stream to Cerpack for ring back.

Theoretically the Dial command with the m option looks to be exactly what I
need:

Dial(SIP/xyz,,m)

This should play musiconhold back to the caller and in my case I just took a
recording of the PSTN tones I wanted to play and created a musiconhold class
for them. The command will work correctly when dialled from a SIP phone
connected to Asterisk but not for calls coming from Cerpack. As far as I can
tell this is because Asterisk won't initiate the RTP stream and waits for a
packet from the client before starting to play the musiconhold, perhaps
assuming the connection is not available until it gets a packet. In this
case Cerpack isn't sending a packet so no audio is heard until the call is
answered.

Has anybody seen anything like this before?

Thanks,

Aaron