When I started using openser I used a patched version of 1.0 nathelper. This patch created two formats for fix_nated_contact. There was the original format -- fix_nated_contact() and the new format fix_nated_contact(1.2.3.4).
The original format appears to be useful for service providers. The new format is useful when you are using openser as an ALG for a home or small office phone system. The contact gets mangled before being sent to the registrar.
Because redoing the patch for each new version of openser that comes along is silly, I had previously asked the list for an alternative. Someone suggested using encode_contact from the mangler modules. This works but I think it is sub-optimal when you have multiple phones with the same user name. Each one creates its own contact with the registrar. The service providers server does the forking and there is a lot of excess messaging with the INVITEs and CANCELs when the call is answered by one of the phones. With fix_nated_contact(1.2.3.4) there is only one location registered and the local openser does the forking and the CANCELs are confined to the LAN.
Comments? Rob