[OpenSIPStack] TCP probems under W2KSP4

[<oth...@in...>]

Hello,

we are currently using the opensipstack and the openSBC for our
client/server development.
Both tools work fine except for TCP,
some SIP packets are bigger than 1300 bytes so TCP must be used according
to the RFCs.

Q: Is this a known problem?

In detail:
TCP sending (forwarding) is OK when the the packet was received via UDP
from a NATed client,
but receiving the response via TCP ends with 3 or more SIP packets (200
OKs) merged in one.
It looks like this is a receiving and sliding TCP window problem. (??)
But in case the NATed client send an INVITE via TCP (about 1495 Bytes)
this is just ignored,
in wireshark I see that the packet was received in TCP/IP stack but it is
never seen in the SIPstack and no tracep output is generated.

I am currently analyzing these problems.
 But if you know already whats the problem it will be very helpfull to
inform me.

(Test & Development Environment:
OpenSipStack 1.1.7, OpenSBC 1.1.4
MS-Windows2000SP4+,
Microsoft Visual Studio 2005 (VC Express)
Version 8.0.50727.762  (SP.050727-7600)
Microsoft .NET Framework Version 2.0.50727)

Thanks in advance and
best regards
Othmar Unger