hi kadota,

-----Original Message----- ������: $BLgED (B $B=_ (B kadota@REL.TRL.MEI.CO.JP) < $BLgED (B $B=_ (B kadota@REL.TRL.MEI.CO.JP)> �ռ���: ITU-SG16@MAILBAG.INTEL.COM ITU-SG16@MAILBAG.INTEL.COM ����: 2000��11��8�� 16:03 ����: About "FACILITY message"

Might I ask a question ? I read "8.2.1 Encapsulation of H.245 Messages within Q.931 Messages" in ITU-T RECOMMENDATION H.323.

The document says,

"When tunneling is active, one or more H.245 messages can be encapsulated

in

any Q.931 message. If tunneling is being utilized and there is no need for transmission of a Q.931 message at the time an H.245 message must be transmitted, then a FACILITY message shall be sent with h323-message-body set to empty."

The encapsulation of H.245 messages is done in the Fast Connect Procedure. Most of the H.245 channel establishment is accomplished in the Fast Connect procedure.

Fast Connect is totally different from H.245 tunneling, they can not coexist.

But there may be H.245 messages that may occur after call establishment that may be sent using the Facility message.

I want to know exactly what are such H.245 messages. Would you tell me those or where in documents to be searched ?

The tunneled H.245 procedure such as MasterSlaveDetermination and CapabilityExchange is not necessarily complete before the Q.931 Call is established. Suppose we want to answer the MasterSlaveDeterminationRequest after Connect is already sent out, where can we tunnle the MasterSlaveDeterminationAck ? So in this situation, we should use Facility.

And, How is the typical sequence of the Fast Connect Procedure including FACILITY messages ?

Facility is not necessary to FastConnect procedure, but if we happen to send a Facility message during the Q.931 call estabilishment procedure,we can put faststart infomation in it.

Best Regards Atsushi Kadota mailto: kadota@rel.trl.mei.co.jp

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