[Serusers] Help!!

[u.prop at virgilio.it]

Hi 
I have the following configuration:

IP Phone ---- router ----- Eth Switch ------ router ------ IP Phone
                                           |
                                           |
                                     PC running SER

If I try to make a call from on IP phone to the other I can get the voice
through
only every second call; I can't get it through everytime I try!
I also tried restarting the routers but it didn't help.

I tried to trace using ngrep and what I can see is that when I have the
speech connection
I get a "loop detected" message from the called phone while when the speech
is not set up
everything looks smooth.

Do you have any suggestion?

Thanks in advance
//Umberto