FQND as Send-by in VIA header

Hallo, 

As I send the FQDN and port instead IP address in VIA header, got
following error.

"javax.sip.TransactionUnavailableException: sentBy does not match the
sentby setting of the ListeningPoint o2-app.o2.open-ims.org:5060
        at
gov.nist.javax.sip.SipProviderImpl.getNewClientTransaction(SipProviderImpl.java:285)"

I checked out source (CVS today), in class
"gov.nist.javax.sip.stack.MessageProcessor", the local IP is used for
host, so FQDN is not allowed?

according to 3261 18.1.1
"   Before a request is sent, the client transport MUST insert a value
of the "sent-by" field into the Via header field.  This field contains
   an IP address or host name, and port.  The usage of an FQDN is
   RECOMMENDED.  This field is used for sending responses under certain
   conditions, described below.  If the port is absent, the default
   value depends on the transport.  It is 5060 for UDP, TCP and SCTP,
   5061 for TLS.
"

urs Lebing