User's Manual 706 Document #: LTRT-27045
Mediant 1000B Gateway & E-SBC
The SIP-I sends calls, originating from the SS7 network, to the SIP network by adding
ISUP messaging in the SIP INVITE message body. The device can receive such a
message from the SIP-I and remove the ISUP information before forwarding the call to the
SIP endpoint. In the other direction, the device can receive a SIP INVITE message that has
no ISUP information and before forwarding it to the SIP-I endpoint, create a SIP-I message
by adding ISUP information in the SIP body. For SIP-I to SIP-I calls, the device can pass
ISUP data transparently between the endpoints.
Figure 37-4: Example of Interworking SIP and SIP-I
For the interworking process, the device maps between ISUP data (including cause codes)
and SIP headers. For example, the E.164 number in the Request-URI of the outgoing SIP
INVITE is mapped to the Called Party Number parameter of the IAM message, and the
From header of the outgoing INVITE is mapped to the Calling Party Number parameter of
the IAM message.
The ISUP data is included in SIP messages using the Multipurpose Internet Mail
Extensions (MIME) body part, for example (some headers have been removed for
simplicity):
INVITE sip:1774567@172.20.1.177;user=phone SIP/2.0
Via: SIP/2.0/UDP 172.20.73.230:5060;branch=z9hG4bK.iI
...
Accept: application/sdp, application/isup, applicatio
Content-Type: multipart/mixed; boundary=unique-bounda
MIME-Version: 1.0
Content-Length: 350
...
Content-Type: application/isup; version=FTSSURI; base
Content-Disposition: signal; handling=required
01 00 40 01 0a 02 02 08 06 83 10 71 47 65 07 08
01 00 00
--unique-boundary-1—
D6 SIP-T ISUP/IAM (Initial address message)
(--) len:-- >> Nature of connection indicators
Oct 1 : ---0---- Echo ctrl = Half echo not included
----00-- Cont. check = Not required
------00 Satellite = No circuit
(--) len:-- >> Forward call indicators
Oct 1 : 01------ ISUP pref. = Not req. all the way
--0----- ISUP indic. = Not used all the way
---0---- End-end inf = Not available
----0--- Interwork. = Not encountered
-----00- Method. ind = No method available
-------0 Call indic. = as National call
Oct 2 : -----00- SCCP method = No indication
ISUP data, received in the MIME body of the incoming SIP message is parsed according
to the ISUP variant (SPIROU itu or ansi), indicated in the SIP Content-Type header. The
device supports the following ISUP variants (configured by the 'ISUP Variant' parameter in
the IP Profile table):
French (France) specification, SPIROU (Système Pour l'Interconnexion des Réseaux
OUverts), which regulates Telecommunication equipment that interconnect with
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