Asterisk SIP/2.0 401 Unauthorized

As this might helps for somebody:

insecure=invite

helped me after a similar relocation. For me it was vm to vm but bridged to the exact same network so I just don't get it why my working configuration stopped to work. I experienced one way call effect. The calls from outside SIP PBX going into the asterisk then sent out to voip softclients were working but the voip softclients couldn't communicate at all.

Issue resolved! Despite Asterisk offering the ability to deal with more than one address by specifying 0.0.0.0 as your listen address, the box on which Asterisk was present was sending invites from other aliased IPs on the server instead of the one intended. Binding Asterisk to one IP, and connecting to that one IP, resolves this issue entirely.