I installed AsteriskNow on a virtual machine (KVM/qemu) and I am just testing their "hello world" example. I am at the beginning of my knowledge in this domain. The example proposes to use the softphone Zoiper.
I "see" in the Asterisk CLI the messages between Asterisk and Zoiper but I don't hear the "hello world" message.
Sorry, I cannot say more but ready to check what you want ;-)
Note:
With wireshark, I see a message between asterisk and zoiper: request bye sip 6001@<ip>:<port> and just after 489 bad event, 401 unauthorize. <ip> is not a local ip but my internet address !?
Asterisk also sends many RTP messages.
Note:
Zoiper confirms the establishment of the connexion and the hangup.