User's Manual 508 Document #: LTRT-10632
Mediant 800B Gateway & E-SBC
5. In the Trunk Group table (see Configuring Trunk Groups on page 517), configure the
Trunk Group ID for the E1/T1 CAS Trunk, as shown in the following example:
Figure 22-10: Configuring Trunk Group for Private Wire
6. In the Trunk Group Settings table (see Configuring Trunk Group Settings on page on
page 519), configure the method for selecting channels for the E1/T1 CAS Trunk to
By Dest Phone Number, as shown in the following example:
Figure 22-11: Configuring Channel Select Method for Private Wire Trunk
7. In the IP-to-Tel Routing table (see Configuring IP-to-Tel Routing Rules on page 549),
configure IP-to-Tel Routing rules.
22.5.3 QSIG Tunneling
The device supports QSIG tunneling over SIP, according to IETF Internet-Draft draft-elwell-
sipping-qsig-tunnel-03 ("Tunnelling of QSIG over SIP") and ECMA-355/ISO/IEC 22535.
This is applicable to all ISDN variants. QSIG tunneling can be applied to all calls or to
specific calls using IP Profiles.
Note: TDM tunneling is applicable to PRI and BRI.
QSIG tunneling sends all QSIG messages as raw data in corresponding SIP messages
using a dedicated message body. This is used, for example, to enable two QSIG
subscribers connected to the same or different QSIG PBX to communicate with each other
over an IP network. Tunneling is supported in both directions (Tel-to-IP and IP-to-Tel).
The term tunneling means that messages are transferred ‘as is’ to the remote side without
being converted (QSIG > SIP > QSIG). The advantage of tunneling over QSIG-to-SIP
interworking is that by using interworking, QSIG functionality can only be partially achieved.
When tunneling is used, all QSIG capabilities are supported and the tunneling medium (the
SIP network) does not need to process these messages.
QSIG messages are transferred in SIP messages in a separate Multipurpose Internet Mail
Extensions (MIME) body. Therefore, if a message contains more than one body (e.g., SDP
and QSIG), multipart MIME must be used. The Content-Type of the QSIG tunneled
message is ‘application/QSIG’. The device also adds a Content-Disposition header in the
following format:
Content-Disposition: signal; handling=required.
QSIG tunneling is done as follows:
Call setup (originating device): The QSIG Setup request is encapsulated in the SIP
INVITE message without being altered. After the SIP INVITE request is sent, the
device does not encapsulate the subsequent QSIG message until a SIP 200 OK
response is received. If the originating device receives a 4xx, 5xx, or 6xx response, it
disconnects the QSIG call with a ‘no route to destination’ cause.
Call setup (terminating device): After the terminating device receives a SIP INVITE
request with a 'Content-Type: application/QSIG', it sends the encapsulated QSIG
Setup message to the Tel side and sends a 200 OK response (no 1xx response is
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