anchor.diff:      %% For UDP transport, local ip is set to [:::] (?)
       #transport{
           proto = udp,
  -        local_ip =  {0,0,0,0,0,0,0,0},
  +        local_ip =  {0,0,0,0,0,0,0,1},
           local_port = RPort1,
           remote_ip = {0,0,0,0,0,0,0,1},
           remote_port = 5071,
  -        listen_ip = {0,0,0,0,0,0,0,0},
  +        listen_ip = {0,0,0,0,0,0,0,1},
           listen_port = 5070
       } = Transp1,
       ok = tests_util:wait(Ref, [ok_1]),
  
positive.code:         local_port = RPort2,
          remote_ip = {0,0,0,0,0,0,0,1},
          remote_port = 5071,
          listen_ip = {0,0,0,0,0,0,0,0},
          listen_port = 5070
      } = Transp2,
      ok = tests_util:wait(Ref, [ok_2]),
  
negative.code: start() ->
      tests_util:start_nksip(),
  
      %% NOTE: using 'any6' as ip for hosts fails in Linux
      %% (it works in OSX)
  
      ok = sipapp_server:start({ipv6, server1}, [
          {from, "sip:server1@nksip"},
          registrar,
          {local_host6, "::1"},
          {transport, {udp, any, 5060}},
          {transport, {udp, "::1", 5060}}]),
  
      ok = sipapp_server:start({ipv6, server2}, [
          {from, "sip:server2@nksip"},
          {local_host, "127.0.0.1"},
          {transport, {udp, any, 5061}},
          {local_host6, "::1"},
          {transport, {udp, "::1", 5061}}]),
  
      ok = sipapp_endpoint:start({ipv6, client1}, [
          {from, "sip:client1@nksip"},
          {transport, {udp, "::1", 5070}}]),
      
      ok = sipapp_endpoint:start({ipv6, client2}, [
          {from, "sip:client2@nksip"},
          {transport, {udp, "::1", 5071}}]),
  
      ok = sipapp_endpoint:start({ipv6, client3}, [
          {from, "sip:client3@nksip"},
  