Hi Vivek The only function of TPKT is to define message boundaries. Annex E has own mechanisms to do this. So basically I think that should be no TPKT header in the Q.931 messages when used with Annex E. Sasha -----Original Message----- From: Vivek Kakkar [mailto:vkakkar@CISCO.COM] Sent: Thursday, September 13, 2001 11:19 AM To: ITU-SG16@MAILBAG.INTEL.COM Subject: H323 Annex E over UDP and TPKT header Hello, I wanted to poll the H323 community regarding the use of TPKT header with H225 message while using AnnexE transport capability. AnnexE makes the UDP a reliable signaling channel. H.323 spec talks of using TPKT header with reliable signaling channel. What is your interpretation of H323/AnnexE regarding the TPKT header? Does the TPKT header have a function in this case? thanks, -- vivek ============================================================= Vivek Kakkar Cisco Systems, Inc. vkakkar@cisco.com Research Triangle Park, NC 919-392-6975:o USA