Etompau, many thanks for your help, anyway.
I got into the admin mode, I have been playing with IPs with no success.
I just got a SIP account; 12345@sarenet.com where 12345 is my user and there is a password too. No IPs, nothing else.
For softphones works good.
Now I did those settings into my DD-WRT MilkFish SIP router (LinkSys WRT54G) but I can not get the Dialog4422 working with that configuration.
So, I am going to buy a "normal" SIP phone, Snom style, and try again.
Thank you again.
PD. If anyone is interested...I'll sell the Dialog4422.