Latency, network and Asterisk problems

Hi all,
I have just set-up a Asterisk server in Denmark and i have 3 phones connected to it. All of them on the same network (no NAT). One of the phones is placed in India and goes thru a VPN box and a WAN optimizer.

All phones registeres to the server and some times it works ok. I saw i had long latency to india which was 300 ms so i disabled qualify on all of them. NAT is also disabled on all of them.

My problem is that when i call from the phone in Denmark to India it dials and i can see in the log that it dials to the other end but if i look at the phone in India on the webinterface it does not ring. If i call between two phone in DK then everything works fine.

In the debug log on the asterisk server i get Retransmitting #3 (no NAT) to x.x.x.x:5060: where x.x.x.x is the ip of the phone in India.

It seems to me there is network problems so my packets does not get to the phone itself. Am i correct ? Can i do more to debug this problem ? Can there be a problem that someone timesout before getting to the phone itself ?

I am using a Sipura SPA962 and a Sipura SPA942

I would appreciate some help to solve this.