I can't make call in asterisk

Hi Everybody,
I followed the “Hello World” asterisk wiki (in this link :https://wiki.asterisk.org/wiki/display/AST/Hello+World ). When I try to make a call, i have a message in Asterisk CLI:

------- strict RTP learning after remote.

In my SIP softphone (i use Zoiper), when i make the call (with the 100 extension), there is no ring tone and some seconds later, i have a message: 408 request timeout.

Thanks for helping me.

Hi Everybody,

Any Ideas ?

The bump time for this forums is 24 hours.

Asterisk’s response didn’t reach the phone. That suggests a network configuration problem.