8 Interactions between control node and MGW
29.1643GPPInterworking between the 3GPP CS domain with BICC or ISUP as signalling protocol and external SIP-I networksRelease 17TS
8.1 Overview
ITU-T H.248.1 [11] with 3GPP specific extensions as detailed in 3GPP TS 29.332 [6] shall be applied as signalling protocol between IWU and MGW.
The present specification describes the signalling procedures between IWU and MGW and their interaction with BICC/ISUP and SIP signalling in the control plane, and with user plane procedures. 3GPP TS 29.332 [6] maps these signalling procedures to H.248 messages and defines the required packages and parameters.
8.2 Signalling interactions
The procedures in Clause 9.2 of TS 29.163 shall be applied with modifications provided in the present Clause.
8.2.1 Backward through-connection for outgoing call interworking from BICC to SIP at O-IWU.
For the outgoing call interworking from BICC to SIP at O-IWU, the IWU shall not request the MGW to provide an awaiting answer indication (ringing tone) to the calling party, as specified in Clauses 9.2.3.1.5, 9.2.3.2.5 and 9.2.3.3.5 of 3GPP TS 29.163 [4]. The O-IWU shall instead request the MGW to backward-through connect using the "Change-IMS Through-Connection" procedure when the trigger conditions in those clauses apply.
8.2.2 Handling of RTP telephone events
The procedures in Clause 9.2.8 of 3GPP TS 29.163 [4], are applicable with the following modifications:
It depends on the characteristics of the external SIP-I network if DTMF is transported within the codec or according to IETF RFC 4733 [28]. SIP-I transports DTMF within the RTP telephony event according to RFC 4733 [28] if the RTP telephony event payload type is negotiated between the peer SIP-I entities; alternatively, if the RTP telephony event payload has not been negotiated, SIP-I may transport the DTMF in-band ("within the codec") when the selected codec allows transparent DTMF transport.
The control node indicates the transport mode of DTMF to the MGW as follows in the “Configure IMS Resources" procedure or "Reserve IMS Connection Point and Configure Remote Resources" procedure (signal 1 in figure 48 or figure 49 of 3GPP TS 29.163 [4]):
– If the control node does not configure the RTP telephony event payload at the MGW, then the Detect DTMF procedure means in-band ("within the codec") detection and sending of DTMF.
– If the control node configures the RTP telephony event payload at the MGW, then the Detect DTMF procedure means extracting and sending DTMF within the RTP payload type according to IETF RFC 4733 [28].
Editor’s Note: The above reference contains sequences that require the MGW to forward partial digits to the Server. It is not yet agreed if this shall be permitted or if the MGW shall only forward complete and valid digits.
8.3 Signalling procedures
The procedures in Clause 9.3 of 3GPP TS 29.163 shall be applied with modifications provided in the present Clause.
The support of the "Send TDM Tone", "Stop TDM Tone", "Send Tone" and "Stop Tone" procedures is optional.
Annex A (normative):
Codec Negotiation between a BICC based CS Domain and an external SIP-I network
The procedures in Annex B of TS 29.163 [4] are applicable when the IWU receives from the external SIP-I based network an SDP offer without the 3GPP_OoBTC_Indicator as defined in 3GPP TS 29.231 [38].
If the IWU receives from the external SIP-I based network a SIP request with an SDP offer containing a codec list with the 3GPP_OoBTC_Indicator, the IWU may apply the procedures in accordance to subclause 6.6.2 of 3GPP TS 29.235 [39].
When the IWU sends a SIP request with an SDP offer towards the external SIP-I based network, the IWU may include the 3GPP_OoBTC_Indicator in accordance to subclause 6.6.3 of 3GPP TS 29.235 [39].
Annex B (informative):
Change history
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Change history |
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Date |
TSG # |
TSG Doc. |
CR |
Rev |
Subject/Comment |
Old |
New |
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01/09/2006 |
CT3#41 |
C3-060509 |
Agreed Skeleton of TR |
0.0.0 |
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15/10/2006 |
Proposed update of the TR on CT3 email reflector NOT discussed or agreed by CT3, but put onto the 3GPP web server drafts folder by mistake. |
0.0.0 |
0.1.0 |
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08/11/2006 |
CT3#42 |
C3-060877 |
Includes the following TDOCs agreed by CT3: |
0.0.0 |
0.2.0 |
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22/02/2007 |
CT3#43 |
C3-070274 |
Includes the following TDOCs agreed by CT3: |
0.2.0 |
0.3.0 |
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28/02/2007 |
TSG#35 |
CP-070100 |
Editorial update by MCC for presentation to TSG CT for information |
0.3.0 |
1.0.0 |
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19/04/2007 |
CT3#43bis |
Includes the following TDOCs agreed by CT3: |
1.0.0 |
1.1.0 |
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15/05/2007 |
CT3#44 |
Includes the following TDOC agreed by CT3: C3-070523 |
1.1.0 |
1.2.0 |
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23/05/2007 |
TSG#36 |
CP-070427 |
Editorial update by MCC for presentation to TSG CT for approval |
1.2.0 |
2.0.0 |
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06/2007 |
TSG#36 |
CP-070427 |
Approved to be made v7.0.0 and put under change control |
2.0.0 |
7.0.0 |
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12/2008 |
TSG#42 |
Upgraded to v8.0.0 due to simple upgrade without no technical change |
7.0.0 |
8.0.0 |
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05/2009 |
TSG#44 |
CP-090350 |
001 |
2 |
Codec negotiation when interworking with BICC based CS CN |
8.0.0 |
8.1.0 |
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12/2009 |
TSG#46 |
Automatic upgrade from previous Release |
8.1.0 |
9.0.0 |
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06/2010 |
TSG#48 |
CP-100323 |
003 |
1 |
Renumbering of duplicated subclauses |
9.0.0 |
9.1.0 |
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10/2010 |
TSG#49 |
CP-100556 |
004 |
Correcting unspecific external reference |
9.1.0 |
9.2.0 |
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03/2011 |
TSG#51 |
Automatic upgrade from previous Release version 9.2.0 |
9.2.0 |
10.0.0 |
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03/2011 |
TSG#51 |
Correction of heading and numbering made by MCC |
10.0.0 |
10.0.1 |
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09/2012 |
TSG#57 |
Automatic upgrade from previous Release version 10.0.1 |
10.0.1 |
11.0.0 |
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2014-10 |
Automatic upgrade from previous Release |
11.0.0 |
12.0.0 |
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2015-12 |
Automatic upgrade from previous Release |
12.0.0 |
13.0.0 |
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TSG # |
TSG Doc. |
CR |
Rev |
Cat |
Subject/Comment |
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2017-03 |
CT#75 |
Automatic upgrade from previous Release |
14.0.0 |
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2018-06 |
CT#80 |
Automatic upgrade from previous Release |
15.0.0 |
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2020-07 |
SA#88e |
– |
– |
– |
Update to Rel-16 version (MCC) |
16.0.0 |
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2022-03 |
SA#95e |
– |
– |
– |
Update to Rel-17 version (MCC) |
17.0.0 |
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