T – Com (Deutsche Telekom)
SOURCE*:
T Com, T332-2 (Roland Jesske)
TITLE:
SIP History Info used for the interworking of PSTN/ISDN Supplementary Services
Abstract: This document discusses the History Info Draft and for what service
interworking it can be used.
The Call forwarding services are not interworkable in a easy way because with
regard to the History Header special rules must be built for the interworking to ISUP
Parameters. E.G the interworking of Redirection counter to a Index number and vice
versa.
There ar also many possible call constructions regarding the forwarding services.
Within ISUP there are 4 Call Forwarding services specified in Q.732. The definition of
and Stage 2 description are shown in Q.82.
Service definitions:
The Call Forwarding Unconditional supplementary service permits a served user to
have the network send to another number all incoming calls for the served user’s
number (or just those associated with a specified basic service). The served user’s
originating service is unaffected. If this service is activated, calls are forwarded no
matter what the condition of the termination.
The Call Forwarding on Busy supplementary service permits a served user to have
the network send to another number all incoming calls for the served user’s number
(or just those associated with a specified basic service) which meet busy at the
served user’s ISDN number. The served user’s originating service is unaffected.
The Call Forwarding on No Reply supplementary service permits a served user to
have the network send to another number all incoming calls for the serviced user’s
number (or just those associated with a specified basic service) which meet no reply
at the served user’s ISDN number. The served user’s originating service is
unaffected.
The Call Deflection supplementary service permits a serviced user to, in real time,
request that the network redirects an incoming call addressed to the served user’s
ISDN number to another number. The served user’s originating service is
The possible identified scenarios with regard to the interworking are the following:
Attention: This is not an Deutsche Telekom (T332) publication made available to the public, but an internal Deutsche
Telekom Document (T332) intended only for use by the companies and their respective staff and collaborators involved in
their work related to above mentioned issue It shall not be made available to, and used by, any other persons or entities
without the prior written consent of Deutsche Telekom (T332).
At I-IWU
Call Forwarding appears in SIP Network or in the ISDN Network
CFB, CFNR, CFU, CD
At O-IWU
Call Forwarding appears in SIP Network or in the ISDN Network
CFB, CFNR, CFU, CD
And of course several concatenations of Call forwarding.
One main Functionality of the SIP network that can be used for the Call forwarding is
the History Header.
With regard to ISUP and the supplemtary Service description in Q.732 the following
Messages and Parameters are used for the call forwarding services.
Address complete message
Optional backward call indicators
Generic notification indicators
Redirection number
Redirection number restriction indicator
Call diversion information
Answer message
Redirection number
Redirection number restriction indicator
Call progress message
Optional backward call indicators
Event indicator
Generic notification indicator
Call diversion information
Redirection number
Redirection number restriction indicator
Connect message
Redirection number restriction indicator
Initial address message
Redirecting number
Redirection information
Original called number
The following parameter fields and codes are used to support the call diversion supplementary service.
H
G
F
E
D
C
B
A
Event information  No Interworking needed
Bits
G F E D C B A
0 0 0 0 0 0 1
ALERTING
0 0 0 0 0 1 0
PROGRESS
0 0 0 0 10 0 0
CFB (see Note)
1
0 0 0 0 1 0 1
CFNR (see Note)
0 0 0 0 11 1 0
CFU (see Note)
Bit
H
0
No indication
1
Presentation restricted (see Note)
NOTE – These codes are used in national networks and can be used on the international interface on bilateral
agreement. If these codes are used and conflicting information is received compared to the generic notification
indicator and the call diversion information parameter, the latter takes priority.
Forward call indicators
Bit
H G
0 0
ISDN user part preference indicator
ISDN user part preferred all the way
Optional backward call indicators
Bit
B
Call diversion indicator
0
No indication
1
Call diversion may occur
Original called number
Redirection information
Bits
C B A
0 1 1
1 0 0
Redirecting indicator
Call diverted
Call diverted, all redirection info presentation restricted
Bits
H G F E
0 0 0 0
Original redirection reasons
Unknown
Bits
K J
Redirection counter
I
Bit
L
Bits
P O
0 0
0 0
0 0
0 0
0 1
0 0
1
0 1
Reserved for national use
N
0
0
1
1
0
0
1
M
0
1
0
1
0
1
0
Redirecting reason  Reason Header
Unknown/not available
User busy
No reply
Unconditional
Deflection during alerting
Deflection immediate response
Mobile subscriber not reachable
Redirecting number
Redirection number
Redirection number restriction indicator
Bits
B A
0 0
0 1
1 0
1 1
Presentation restriction indicator  Privacy Header Field
Presentation allowed
Presentation restricted
Spare
Spare
Bits
H G F E D C
Generic notification indicator
Bits
G F E D C B A
1 1 1 1 0 1 1
Call diversion information
Bits
C B A
0 0 0
0 0 1
0 1 0
0 1 1
Bits
G F E D
0 0 0 0
0 0 0 1
0 0 1 0
0 0 1 1
0 1 0 0
`
0 1 0 1
0 1 1 0
Spare
Call is diverting
Notification subscription option  Privacy Header Field
Unknown
Presentation not allowed
Presentation allowed with redirection Nb
Presentation allowed without redirection Nb
Redirecting reason  Reason Header(new Reason Values needed)
Unknown/not available
User busy
No reply
Unconditional
Deflection during alerting
Deflection immediate response
Mobile subscriber not reachable
The following sections shows the proposed interworking for several Call forwarding scenarios.
1.
2.
3.
4.
Interworking at the O-IWU with call forwarding in SIP
Interworking at the O-IWU with call forwarding in ISUP
Interworking at the I-IWU with call forwarding in SIP
Interworking at the I-IWU with call forwarding in ISUP
1.1 Interworking at the O-IWU
1.1.1 Call forwarding within the SIP Network.
Originating
Exchange
UA-1
O-IWU
UA-2
Proxy1
IAM
INVITE
INVITE
100 Trying
(Note 1)
486
ACK
ACM
INVITE
181 Call Forwarded
CPG
180 Ringing
ANM
180 Ringing
200 OK
200 OK
[ SDP, ANM ]
ACK
ACK
Figure 1 Call Forwarding Busy
For the mapping of IAM to the INVITE Message no additional procedures beyond the basic call procedures are
needed.
With regard to the Backward Messages the following mapping is valid:
Message sent to ISUP
Message Received from SIP
ACM indicating call forwarding
181
CPG indicating Cal Diversion
181
ACM indicating ringing
180
CPG indicating Alerting
180
ANM
200 OK
CON
200 OK
Table 1 : Mapping of 181 Forwarding  ACM
181
History
Header
ACM
Optional backward
call indicators
<sip:e164-User2@UA2?Reason:SIP;
cause=486 ;text="Busy >;index=2.1,
appropriate global number portion of
the URI, assumed to be in form
"+" CC+NDC+SN
Generic
notification
indicators
Redirection
number
Bit B
call diversion may occur
Call is diverting
Nature of address indicator:
If CC is equal to the country
code of the country where IIWU is located AND the next
BICC/ISUP node is located in
the same country then set to
“national (significant)
number”
else set to “international
number”
Address Signals
If NOA is “national
(significant) number” then set
to
NDC + SN.
If NOA is “international
number”
then set to CC+NDC+SN
Priv-value
Priv-value
“user”
“header”
proposed Values for History
“History-Index”
“History-header”
Privacy header field absent
or
“none”
“header”
proposed Values for History
“History-Index” or “History-header”
and
Privacy header field absent or “none”
Privacy header field absent or “none”
History Index
Reason Header: Reason = “Q.732”
Unknown/not available
Redirection
number restriction
indicator
presentation restricted
presentation restricted
Presentation allowed or absent
Call diversion
information
Notification
subscription
options
presentation not allowed
presentation allowed without
redirection number
presentation allowed with
redirection number
Call diversion
information
Redirecting Reason
User busy
User busy
no reply
No reply
unconditional
Unconditional
Unconditional
Deflection during alerting
Deflection during alerting
Deflection immediate response
Deflection immediate response
Mobile subscriber not reachable
Reason Header: Reason = “Q.850”
Mobile subscriber not reachable
SIP Reason 486  Busy Here
User busy
SIP Reason 487  Call terminated
no reply
???
unconditional
180 Ringing  ACM or CPG
Table 2 : Mapping of 181 Forwarding  CPG if ACM was already sent
180
CPG
Optional backward
call indicators
call diversion may occur
Generic
Call is diverting
History-header <sip:e164-User2@UA2?Reason:SIP;
cause=486 ;text="Busy here”
>;index=2.1,
Cause 486 in History Index
notification
indicators
Event indicator
PROGRESS
Or
Based on the Index entry
CFB(national use)
CFNR(national use)
CFU(national use)
Note [RJ]: I think Alerting is the
correct one
History
Header
See Table 1
Redirection
number
See Table 1
Priv-value
See Table 1
Redirection
number restriction
indicator
See Table 1
Priv-value
See Table 1
See Table 1
Reason
Header
Reason =
“Q.732”
Or
History Index
See Table 1
Call diversion
information
Notification
subscription
options
Call diversion
information
Redirecting
Reason
See Table 1
Table 3 : Mapping of 180  ACM if no 181 was received before
180
History
Header
ACM
If Index indicate that there is a call
forwarding.
Optional backward
call indicators
Bit B
no indication
call diversion may occur
Generic
notification
indicators
Call is diverting
More than two index entries with two
digits Index X.X
History
Header
If Index indicate that there is a call
forwarding.
More than two index entries with two
digits Index X.X
History
Header
See Table 1
Redirection
number
See Table 1
Priv-value
See Table 1
Redirection
number restriction
indicator
See Table 1
Priv-value
See Table 1
Call diversion
information
Notification
subscription
options
See Table 1
Reason
Header
Call diversion
information
Redirecting
Reason
See Table 1
Reason =
“Q.732”
See Table 1
Or
History Index
The IWU can indicate the call diversion in the mapping of 180 to CPG in fact if the response before was a 181.
Table 4 : (CFB) Mapping of 180  CPG if a 181 was received before
180
CPG
Optional backward
call indicators
History-header <sip:e164-User2@UA2?Reason:SIP;
cause=486 ;text="Busy here”
>;index=2.1,
Cause 486 in History Index
Generic
notification
indicators
Event indicator
call diversion may occur
Call is diverting
ALERTING
Note [RJ]: I think Alerting is the
correct one
History
Header
See Table 1
Redirection
number
See Table 1
Priv-value
See Table 1
Redirection
number restriction
indicator
See Table 1
Priv-value
See Table 1
See Table 1
Reason
Header
Reason =
“Q.732”
Or
History Index
See Table 1
Call diversion
information
Notification
subscription
options
Call diversion
information
Redirecting
Reason
See Table 1
Table 5 : (CFB) Mapping of 200OK
200 OK
History
Header
See Table 1
Priv-value
See Table 1
ANM
Redirection
number
Redirection
number restriction
indicator
See Table 1
See Table 1
Originating
Exchange
UA-1
O-IWU
IAM
UA-2
Proxy1
INVITE
INVITE
100 Trying
(Note 1)
180 Ringing
ACM
180 Ringing
timeout
CANCEL
487
ACK
CPG
INVITE
181 Call Forwarded
CPG
180 Ringing
ANM
180 Ringing
180 Ringing
200 OK
[ SDP, ANM ]
ACK
ACK
Figure 2 Call Forwarding Non Reply
Originating
Exchange
UA-1
O-IWU
IAM
UA-2
Proxy1
INVITE
INVITE
100 Trying
ACM
CPG/ACM
ANM
181 Call Forwarded
(Note 1)
180 Ringing
200 OK
[ SDP, ANM ]
ACK
INVITE
180 Ringing
200 OK
ACK
Figure 3 Call Forwarding Unconditional
(Note 1) It is implementation dependent if the 181 will be send from a Proxy.
1.1.2 Call forwarding within the ISUP Network.
The following Scenario shows if a Call Forwarding appears in the ISUP/PSTN Network and the redirected
Number is within the SIP Network. The following Figure should be seen as example.
Figure 3: Call Forwarding in the ISUP Network with diverted Number in SIP Network
B
LE B
LE A
IAM
UA-A
O-IWU
SETUP
Busy
ACM
IAM
CPG
ACM
ANM
INVITE
180
200
ANM
Figure 4 Call Forwarding Busy in a ISUP network to a SIP User Agent
For the mapping of 180 and 200 OK to the regarding ISUP messages and parameters no additional procedures
beyond the basic call procedures are needed.
IAM
Redirecting
number
Nature of address indicator:
If CC is equal to the country code
of the country where I-IWU is
located AND the next BICC/ISUP
node is located in the same country
then set to “national (significant)
number”
INVITE
History Header
<sip:e164UserB@UA2?Reason:SIP;
cause=486 ;text="Busy
>;index=2.1,
else set to “international number”
Add CC (of the country where
the IWU is located) to Generic
Number Address Signals then
map to user portion of URI
scheme used.
Address Signals
Map complete Redirection
number Address Signals to user
portion of URI scheme used.
if NOA is “national (significant)
number” then the format of the
address signals is:
NDC + SN
If NOA is “international number”
then the format of the address
signals is:
CC + NDC + SN
display-name may be mapped
from Address Signals, if
possible and network policy
allows it
Addr-spec
"+” CC NDC SN mapped to
user portion of URI scheme
used
Redirecting
number
APRI
Privacy Header
Priv-value
“presentation restricted”
proposed Values for History
“History-Index” or “Historyheader”
“presentation allowed”
Privacy header field absent or
“none”
Redirecting
Information
Redirection indicator
Call diverted
Call diverted, all redirection info
presentation restricted
Privacy Header
Unknown/not available
Priv-value
“none”
proposed Values for History
“History-header” or
“header” (if P-Asserted-ID is “id”)
Index number for Redirecting
number = value of redirecting
counter
Reason Header: Reason =
“Q.732”
User busy
Redirecting
Information
Redirection counter
1 …5
History Index
Redirecting
Information
Redirecting Reason
History Index
User busy
no reply
No reply
unconditional
Unconditional
Unconditional
Deflection during alerting
Deflection during alerting
Deflection immediate response
Deflection immediate response
Mobile subscriber not reachable
User busy
Mobile subscriber not reachable
Reason Header: Reason =
“Q.850”
SIP Reason 486  Busy Here
no reply
SIP Reason 487  Call terminated
unconditional
Original
Called Party
Number
See Redirecting number
Original
Called Party
Number
APRI
To header and
Redirecting number
first Index entry of
History Header
<sip:oCdPN@UA2?Reason:732;
cause=XXX ;text="XXX”>
;index=1,
Privacy Header
Priv-value
“presentation restricted”
proposed Values for History
“History-Index” or “Historyheader”
Note: depended on the privacy
statement for the redirecting
number
“presentation allowed”
Privacy header field absent or
“none”
1.2 Interworking at the I-IWU
1.2.1 Call forwarding within the ISUP Network.
Message sent to SIP
Message Received from BICC/ISUP
INVITE
IAM
181
ACM indicating call forwarding
180
ACM indicating ringing
181
CPG indicating call forwarding
180
CPG indicating ringing
200 OK
ANM
200 OK
CON
Figure 4: Call Forwarding Busy
B
UA-A
LE B
I-IWU
INVITE
IAM
C
LE B
SETUP
100 Trying
Busy
181
ACM
IAM
180
CPG
ACM
200 OK
ANM
ANM
SETUP
ALERTING
CONNECT
ACK
In case of a call forwarding a ACM with a Optional backward call indicator indicating that call
diversion may occur and a Generic notification Call is diverting a 181 shall be send in backward
direction.
Table 5: ACM  181 Forwarding
ACM
Optional
backward call
indicators
Generic
notification
indicators
Redirection
number
181
Bit B
call diversion may occur
Call is diverting
Nature of address indicator:
If CC is equal to the country code
of the country where I-IWU is
located AND the next BICC/ISUP
Based on the ISUP Parameter the
181 message is created
History Header
<sip:e164UserB@UA2?Reason:SIP;
cause=486 ;text="Busy
>;index=2.1,
node is located in the same country
then set to “national (significant)
number”
Add CC (of the country where
the IWU is located) to Generic
Number Address Signals then
map to user portion of URI
scheme used.
else set to “international number”
Map complete Redirection
number Address Signals to user
portion of URI scheme used.
Address Signals
if NOA is “national (significant)
number” then the format of the
address signals is:
NDC + SN
display-name may be mapped
from Address Signals, if
possible and network policy
allows it
If NOA is “international number”
Addr-spec
"+” CC NDC SN mapped to
user portion of URI scheme
used
then the format of the address
signals is:
CC + NDC + SN
Redirection
number
restriction
indicator
presentation restricted
Priv-value
presentation restricted
Presentation allowed or absent
Call diversion
information
Notification subscription options
presentation not allowed
Priv-value
presentation allowed without
redirection number
Redirecting Reason
proposed Values for History
“History-Index”
“History-header”
Privacy header field absent
or
“none”
“header”
proposed Values for History
“History-Index” or “Historyheader”
and
Privacy header field absent or
“none”
Privacy header field absent or
“none”
presentation allowed with redirection
number
Call diversion
information
“user”
“header”
History Index
Unknown/not available
Reason Header: Reason =
“Q.732”
User busy
User busy
no reply
No reply
unconditional
Unconditional
Unconditional
Deflection during alerting
Deflection during alerting
Deflection immediate response
Deflection immediate response
Mobile subscriber not reachable
User busy
Mobile subscriber not reachable
Reason Header: Reason =
“Q.850”
SIP Reason 486  Busy Here
no reply
SIP Reason 487  Call terminated
unconditional
A received CPG shall be mapped t a 180 if the CPC indicates a Alerting is due to the mapping ruled
defined within the basic call.
Table 6: Mapping of CPG  181
CPG
Optional
backward call
indicators
Event
Indicator
181
call diversion may occur
Not relevant ?
CFB(national use)
CFNR(national use)
CFU(national use)
Call is a diverting Call
Generic
notification
Indicator
Redirection
See Table 5
number
Call Diversion See Table 5
Information
Redirection
See Table 5
number
restriction
indicator
Based on this Information the
CPG shall be mapped to a 181
History Header
See Table 5
History Header
See Table 5
Priv-value
See Table 5
Table 7: (CFB) Mapping of ANM/CON  200OK
ANM
Redirection
number
Redirection
number
restriction
indicator
See Table 5
200
History Header
See Table 5
See Table 5
Priv-value
See Table 5
Figure 5: Call Forwarding Non Reply
B
UA-A
INVITE
IAM
C
LE B
LE B
I-IWU
SETUP
100 Trying
Timeout
ACM
180
SETUP
IAM
181
ALERTING
ACM
CPG
DISC
REL
RLC
200 OK
CONNECT
ANM
ANM
ACK
Figure 6: Call Forwarding Unconditional
B
UA-A
INVITE
IAM
C
LE B
LE B
I-IWU
SETUP
100 Trying
180
181
200 OK
SETUP
ACM
IAM
CPG
ACM
ALERTING
CONNECT
ANM
ANM
ACK
1.2.2 Call forwarding within the SIP Network.
UA-1
UAC
I-IWU
Proxy1
INVITE
INVITE
100 Trying
181 Call Forwarded
(Note 1)
180 Ringing
200 OK
[ SDP, ANM ]
ACK
INVITE
IAM
180 Ringing
ACM
200 OK
ANM
ACK
Figure 8 Call Forwarding Busy in a ISUP network to a SIP User Agent
For the mapping of 180 and 200 OK to the regarding ISUP messages and parameters no additional procedures
beyond the basic call procedures are needed.
INVITE
History
Header
<sip:e164-User2@UA2?Reason:SIP;
cause=486 ;text="Busy >;index=2.1,
IAM
Redirecting
number
appropriate global number portion
of the URI, assumed to be in form
"+" CC+NDC+SN
Nature of address indicator:
If CC is equal to the country
code of the country where IIWU is located AND the next
BICC/ISUP node is located in
the same country then set to
“national (significant) number”
else set to “international number”
Address Signals
If NOA is “national
(significant) number” then set
to
NDC + SN.
If NOA is “international
number”
then set to CC+NDC+SN
Privacy
Header
Privacy
Header
&
Index History
> 1 or 1.1
History Index
Priv-value
Redirecting
number
APRI
proposed Values for History
“History-Index” or “History-header”
“presentation restricted”
Privacy header field absent or
“none”
“presentation allowed”
Priv-value
“none”
proposed Values for History
“History-header” or
“header” (if P-Asserted-ID is “id”)
Index number for Redirecting number
Redirecting
Information
Redirection indicator
Call diverted (based on
Invormation given in the historyIndex header this parameter is set)
Call diverted, all redirection info
presentation restricted
Redirecting
Information
Redirection counter = Value Index
number for Redirecting number
If Value >5 then release Call
History Index
Reason Header: Reason = “Q.732”
User busy
Redirecting
Information
Redirecting Reason
Unknown/not available
no reply
User busy
unconditional
No reply
Unconditional
Unconditional
Deflection during alerting
Deflection during alerting
Deflection immediate response
Deflection immediate response
Mobile subscriber not reachable
Reason Header: Reason = “Q.850”
Mobile subscriber not reachable
SIP Reason 486  Busy Here
User busy
SIP Reason 487  Call terminated
no reply
unconditional
To header and
first Index
entry of
History
Header
Privacy
Header
Redirecting number
<sip:oCdPN@UA2?Reason:732;
cause=XXX ;text="XXX”>
;index=1,
Priv-value
Original Called
Party Number
See Redirecting number
Original Called
Party Number
APRI
proposed Values for History
“History-Index” or “History-header”
Note: depended on the privacy
statement for the redirecting number
“presentation restricted”
Privacy header field absent or
“none”
“presentation allowed”
2 ANNEX
This list is a draft list.
SUPPL Party ISUP- SIPService
SIP ISUP
CFB
B(A)
No
No
CFNR
B(A)
No
No
SIP-SIP Service ISUP Parameter
definiti
on in
SIP
Yes
http://ww 1) Optional backward call
w.ietf.or indicators
g/interne 2) Generic notification
tindicators
drafts/dr 3) Redirection number
aft-ietf- 4) Redirection number
sipping- restriction indicator
service- 5) Call diversion
example information
s-04.txt 6) Event indicator
7) Original called number
8) Redirection information;
Yes
1) Optional backward call
indicators
2) Generic notification
indicators
3) Redirection number
4) Redirection number
restriction indicator
5) Call diversion
information
6) Event indicator
7) Original called number
8) Redirection information;
DSS1 Parameter
Facility Nachricht
Notification indicator information
element
Redirecting number information
element
Facility Nachricht
Notification indicator information
element
Redirecting number information
element
SUPPL Party ISUP- SIPService
SIP ISUP
CFU
B(A)
No
No
SIP-SIP Service ISUP Parameter
definiti
on in
SIP
Yes
http://ww 1) Optional backward call
w.ietf.or indicators
g/interne 2) Generic notification
tindicators
drafts/dr 3) Redirection number
aft-ietf- 4) Redirection number
sipping- restriction indicator
service- 5) Call diversion
example information
s-04.txt 6) Event indicator
7) Original called number
8) Redirection information;
DSS1 Parameter
Facility Nachricht
Notification indicator information
element
Redirecting number information
element