Download Proposed Text for Annex in T.38 to support V.150.1 (V.MoIP) and T

ITU - Telecommunications Standardization Sector
Q1103-003
Study Group 16 – Question 11
Location:
Streatley, Berkshire, UK. 18th – 20th March 2003
Source:
Title:
Contact:
Q11/16 Rapporteur
Proposed Text for Annex in T.38 to support V.150.1 (V.MoIP) and T.38 operation
Keith Chu
Tel: +1 949 579 4121
Conexant Systems Inc
Fax: +1 949 579 3667
USA
Email: [email protected]
ABSTRACT
Proposed new Annex to T.38 describing V.150.1 and T.38 interworking. Agreed by Q14/16 as baseline
text for T.38. Provided for the information of Q11/16
Attention: This is not a publication made available to the public, but an internal ITU-T Document intended only for use by the
Member States of the ITU, by ITU-T Sector Members and Associates, and their respective staff and collaborators in their ITU
related work. It shall not be made available to, and used by, any other persons or entities without the prior written consent of the
ITU-T.
Q1103-003
Annex F
Procedures for the Inter-working of T.38 and V.150.1 functions when supported in the
same gateway
This Annex describes the procedures that may be used by Gateways that have both T.38 and
V.150.1 capabilities in the same gateway. Such a gateway shall indicate these capabilities by use
of the appropriate external signaling mechanism (H.323, H.248, SIP/SIP-T or similar) as defined
in the relevant Recommendations. The term FoIP and MoIP as used in this Annex are
synonymous to ITU-T Recommendations T.38 and V.150.1 respectively.
This type of gateway shall only transition to FoIP from MoIP. This Annex does not include any
transitions directly from audio to FoIP nor do they replace the audio and T.38 configuration
procedures as defined in Annexes B, D and E of T.38.
A gateway with these joint capabilities shall initially behave as a V.150.1 gateway. That is all the
call discrimination procedures up to the point at which T.38 procedures are invoked are defined
in section 20 of V.150.1. The transition from MoIP to FoIP occurs when a gateway (in MoIP
mode) detects and verifies the presence of a T.30 facsimile signal such as V.21 Channel 2 HDLC
encoded FLAGS or a V.8 CM signal on the telephony link to the Gateway.
This switching mechanism shall use State Signaling Event protocol (SSE) as defined in
V.150.1/Annex C. Figure F.1 and Figure F.2 illustrate this transition for two facsimile triggering
events. Figure 1 shows a transition to Standard G3 facsimile and Figure 2 shows a similar
transition to V.34 facsimile.
Upon the detection of a Facsimile event the gateway shall transmit a SSE:f(RIC) to the peer
gateway. Where SSE:f is the FAX RELAY SSE transition indication. RIC are reason identifier
codes and are defined below in clause F.X. The use of SSE shall comply with V.150.1/Annex C.
F1
G2
G1
F2
Audio
Audio
)
21Flags
SSE:f(V
SSE:f(p'
)
Facsimile/
T.38
T.38
Link 1
V.21(H) Flags
Facsimile/
T.38
Link 2
Figure F.1/T.38 - T.38 FoIP (MoIP transition to T30 Fax)
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F1
G2
G1
V.8-CM=V.34 fax
Facsimile/
T.38
Audio
F2
Audio
SSE:f(v8
Fax
Profile)
)
SSE:f(p'
Facsimile/
T.38
Link 1
T.38
Link 2
Figure F.2/T.38 - T.38 FoIP (MoIP transition to V34 fax)
V.150.1 defines the SSE:f event code in section C.5.2 and it has the value of 4 decimal .
F.X SSE Reason Identifier Codes for T.38 transition
The following RIC are defined for the SSE:f event:
V21Flags: This RIC indicates that the Gateway has detected and verified that has received
HDLC flags modulated on V.21 Channel 2 as defined in T.30.
V8FaxProfile: This RIC indicates that the Gateway has received a V.8 CM sequence that is a
valid Facsimile connection request. This RIC has as additional information which is the Profile
and T.66 codes (if present) that is used in the “t30-data(cm_message)” of T.38.
P’ State Transition: This is the same signal as used in MoIP. The value is chosen to be
consistent with V.150.1.
The table below summarizes the RIC for T.38 SSE’s.
Name
Code
(decimal)
Additional Informational Content
Null
0
None
V21Flags
1
None
V8FaxProfile
2
“cm_message”
p’ State
Transition
19
None
In both examples, the use of SSE:f may be used as an equivalent signal from T.38. For example
SSE:f(V21Flags) may be used as t30-indicator:FLAGS and SSE:f(V8FaxProfile(cm_message))
may be used as t30-data:cm_message.
A gateway is not required to wait for the SSE:f(p’) message in response to its SSE:f request. The
gateway shall transmit the equivalent T.38 IFP message immediately after issuing the SSE:f
request. The Gateway shall then follow the procedures as defined in this Recommendation.
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External signaling
The use of SSE’s are negotiated during the call set up phase. Annexes E and F of V.150.1 describe the
SDP and H.323 syntax accordingly to be incorporated by a MoIP/FoIP gateway.
Note: The definition of the H.248 syntax for V.150.1 is to be defined.
References:
[1] ITU-T Recommendation V.150.1 – 2003 - Procedures for the END-TO-END connection
of V-series DCEs over an IP Network.
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