[Serusers] Ser fowards invite on wrong IP Address

[Stephen]

If I have Ser listening on two IP addresses it will forward a Invite 
from the address it received it on and not from the address the target 
registered at. This will cause a Nat problem as there will be no binding 
  for that combination.
In the example below Stephen is registered at xxx 162 and 888 at xxx 163 
  and both are behind the same Nat. A call is attempted in each direction.

Is this the correct behavior?


       Source                Destination           Protocol Info
     202.76.176.229        206.123.107.162       UDP      Source 
port:5061  Destination port: 5060
     202.76.176.229        206.123.107.163       SIP/SDP  Request: INVITE
sip:stephen at blablabla.com.au, with session description
     206.123.107.163       202.76.176.229        SIP      Status: 100
trying -- your call is important to us
     206.123.107.163       202.76.176.229        SIP/SDP  Request: INVITE
sip:stephen at 202.76.176.229:5061;user=phone, with session description
     206.123.107.163       202.76.176.229        SIP/SDP  Request: INVITE
sip:stephen at 202.76.176.229:5061;user=phone, with session description
     206.123.107.163       202.76.176.229        SIP/SDP  Request: INVITE
sip:stephen at 202.76.176.229:5061;user=phone, with session description
     202.76.176.229        206.123.107.163       SIP      Request:
OPTIONS sip:sip.blablabla.com.au
     206.123.107.163       202.76.176.229        SIP      Status: 404 Not
Found
     206.123.107.163       202.76.176.229        SIP/SDP  Request: INVITE
sip:stephen at 202.76.176.229:5061;user=phone, with session description
     202.76.176.229        206.123.107.163       SIP      Request: CANCEL
sip:stephen at blablabla.com.au
     206.123.107.163       202.76.176.229        SIP      Status: 200 ok
-- no more pending branches
     206.123.107.163       202.76.176.229        SIP      Status: 487
Request cancelled
     202.76.176.229        206.123.107.163       SIP      Request: ACK
sip:stephen at blablabla.com.au
     202.76.176.229        206.123.107.162       UDP      Source port:
5061  Destination port: 5060
     202.76.176.229        206.123.107.162       SIP/SDP  Request: INVITE
sip:888 at blablabla.com.au;user=phone, with session description
     206.123.107.162       202.76.176.229        SIP      Status: 100
trying -- your call is important to us
     206.123.107.162       202.76.176.229        SIP/SDP  Request: INVITE
sip:888 at 202.76.176.229:5060, with session description
     206.123.107.162       202.76.176.229        SIP/SDP  Request: INVITE
sip:888 at 202.76.176.229:5060, with session description
     206.123.107.162       202.76.176.229        SIP/SDP  Request: INVITE
sip:888 at 202.76.176.229:5060, with session description
     206.123.107.162       202.76.176.229        SIP/SDP  Request: INVITE
sip:888 at 202.76.176.229:5060, with session description
     202.76.176.229        206.123.107.162       SIP      Request: CANCEL
sip:888 at blablabla.com.au;user=phone
     206.123.107.162       202.76.176.229        SIP      Status: 200 ok
-- no more pending branches
     206.123.107.162       202.76.176.229        SIP      Status: 487
Request cancelled
     202.76.176.229        206.123.107.162       SIP      Request: ACK
sip:888 at blablabla.com.au;user=phone