Using NAT networking in VMware? If so, the UNI system may have ‘guest isolation’ or similar. Run Wireshark on the host and see whether REGISTER requests are reaching it. If so, run tcpdump on the guest and see if the requests are being properly forwarded. If so, at the Asterisk command prompt, do
sip set debug on
and see whether the requests are being seen by Asterisk and what response, if any, is being sent back.
I know little about VMware, but was hoping that the guest would see the dongle or Ethernet NIC as its own device, which would be the only network interface on the guest.