Iñaki Baz Castillo writes:
Unfortunatelly such 408 is painful as the examples above show. This is the reason I propose TM to generate a local 503 if no response at all is received for a UDP requests (when fr_timer expires).
inaki,
from rfc3261:
21.4.9 408 Request Timeout The server could not produce a response within a suitable amount of time, for example, if it could not determine the location of the user in time.
1.5.4 503 Service Unavailable The server is temporarily unable to process the request due to a temporary overloading or maintenance of the server.
if there is no response from server, there is no way for the proxy to know that the server is "temporarily overloaded or under maintenance". it seems that 503 needs to come from the server itself. so in this case 408 looks a more appropriate response to me.
-- juha