Unable to register more than a number

if I have ONE register directive in sip.conf all is going well: incoming and outcoming calls, pap2 registration, etc…

today i activated a second voip number and inserted the second register line, and added a friend block in the sip.conf. All of registrarion data are corrects, but …

… NONE OF 2 numbers is able to register from now. ’ timeout’

if I leave the first or the second number ‘alone’, well it’s registering with no problem, but it’s impossible to keep both

So i change voip provider, but it’s the same, having more than one register will make crazy asterisk. No error, only ‘timeout’, and my local pap2 is unable to login. but locale number is NOT changed in config options.

Why this?