IP330 not ringing.

Hi,

I have IP330s, all of them on NAT. Firewall has opened 5060 and 8000-20000 ports. The Asterisk server is on a public IP with no hardware firewall or iptables. They are also set to nat=yes, and under general canreinvite=no.

When these phones make outbound calls, they work just fine. Full two-way audio.
However, when these phones are in a queue and when calls come to the queue, the phones physically don't ring.

Also, the phones do not ring physically or in the ear piece when called from each other.
They've been provisioned via FTP.

In this same network, I have Aastra 9133i phones which work flawlessly. So I don't think it's a firewall/NAT issue.

Please help.