User's Manual 504 Document #: LTRT-10632
Mediant 800B Gateway & E-SBC
and multi-channel speaker units, allowing immediate connection with multiple parties (e.g.,
30 channels). These channels remain constantly open throughout the trading day.
Today, private wire services are evolving from digital TDM architectures to IP-based
architectures. The device can be used for interworking between these two architectures,
where you have the PSTN switch (PBX) using the E1/T1 CAS protocol on one side, and a
SIP-based private wire (turret system) trunk on the other side. The device converts the
CAS channels into a SIP call with a called and calling number and if required, passes the
ABCD bit state changes through SIP messages, and vice versa. The following diagram
shows an example of private-wire interworking by the device:
Figure 22-5: Example of Private Wire System
SIP-based private wire calls are established as any other INVITE dialog, but with the
addition of the following headers:
SIP Supported header with the value "pw-info-package" (i.e., Supported: pw-info-
package).
SIP Recv-Info header with the value "pw-info-package" and with the parameter "pw-
type=" with a value denoting the private wire state, which can be:
• Ring Down state:
Recv-Info: pw-info-package;pw-type=ringdown
• Hook Switch:
Recv-Info: pw-info-package;pw-type=hookswitch
• TOS:
Recv-Info: pw-info-package;pw-type=tos
The following is an example of an INVITE message for a private wire call:
INVITE sip:109701@10.221.108.249:5060;transport=tcp SIP/2.0
Via:SIP/2.0/TCP10.221.109.4:5060;oc-
node=101;branch=z9hG4bKqkYGTNi7Husc11Jlmw6d9g;rport
From: <sip:uas@10.221.109.4>;tag=ENvIDQ
To: <sip:109701@10.221.108.249:5060;transport=tcp>
Call-ID: WHuqvQgdIZB27ewgrhJRYw
CSeq: 835392 INVITE
Contact: <sip:10.221.109.4:5060;transport=tcp;oc-node=101>
Max-Forwards: 70
Content-Type: application/sdp
Content-Length: 635
Supported: pw-info-package
Recv-Info: pw-info-package;pw-type=ringdown
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