asterisk users - Feb 2006 - SIP ATA gives no ring tone on IAX2 route

Hello everybody,

I have this problem where I can't get a ring tone when
SIP devices dial an IAX2 route. I get the ring tone
using IAX2 devices to dial the same route. The call
completes normally in both cases...

Facts:
- Asterisk 1.0.9
- The Dial command is within an AGI.
- ATA (grandstream) and firefly (SIP mode) would not give me the ring tone 
at all
- Switching to a SIP route works ok
- Dial with -r option did not do it, same result
- I tried progressinband=yes in sip.conf but with no success.

So my question is, where should I look for to make sure
that my SIP devices will always ring ? Even Asterisk ring tone
would do it for now. Any particular settings ?  Is sip reload
full proof can I use being certin all settings will take effect ?

Thanks a lot folks !
Fred