[Sip] INVITE after terminated dialog?

Hi All,

There is a weird situation with us:
(1) A Linksys phone sends an INVITE out with incorrect destination TN.
As a result, our application server will set up a call between the
Linksys phone and an IVR
(2) A user incorrectly hits the on-hold key, which is basically sending
a re-INVITE to the IVR
(3) Our server seems to have answered the re-INVITE with a BYE
(4) The Linksys phone responds to the BYE with a 200
(5) Afterwards, the Linksys phone still thinks that its original
re-INVITE has not been responded.  So, it will keep resend re-INVITE

The consequence of these re-INVITEs is a registration migration, which
we don't like.  We have been trying to figure out which side is not
following RFC 3261, the phone, the SBCs are wrong, or the application
servers.

I am wondering:
(A) Is it legal for a server to ignore the re-INVITE and respond with a
BYE and has nothing in between?

(B) If a UA has responded to a BYE with 200, is it supposed to forget
about the re-INVITE request that it has sent out and not try to resend
the re-INVITE, assuming a dialog has already been terminated with the
BYE/200 transaction?  Maybe in another sentence, is it legal to send our
re-INVITEs outside an dialog, even if these re-INVITEs are the repeats
of an original in-dialog re-INVITE?

Thanks!

Jane