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Ill IIII Illl IIII11IIIIIIIII
United States Patent [w]
 SIGNALING NETWORK GATEWAY DEVICE AND METHOD FOR USE IN A SIGNALING NETWORK
 Inventor: Frederick H. Skoog, 127 Cheeksparger Rd., Colleyville, Tex. 76034
 Appl. No.: 08/840,866  Filed: Apr. 16, 1997
 Int. CI.7 H04M 7/00; H04J 3/02;
 U.S. CI 379/230; 370/401; 370/467;
 Field of Search 379/207, 219,
379/220, 221, 229, 230; 370/401, 466, 467, 389, 422
 References Cited
U.S. PATENT DOCUMENTS
5,099,475 3/1992 Kozaki et al 370/422
5,420,916 5/1995 Sekiguchi 379/230
5,613,068 3/1997 Gregg et al 370/389 X
5,640,446 6/1997 Everett et al 379/115
5,838,782 11/1998 Lindquist 379/207 X
FOREIGN PATENT DOCUMENTS
0317170 5/1989 European Pat. Off H04L 11/20
9315583 8/1993 WIPO H04M 7/00
Barnes, Tony, "Gateway to the World," Telesis, 1991, pp. 15-25.
Primary Examiner—Harry S. Hong
Patent Number: 6,081,591 Date of Patent: Jun. 27,2000
A signaling network gateway device (12) is provided for use in a signaling network (10), such as a Signaling System 7 signaling network. The signaling network gateway device (12) includes a protocol interlace unit, a signaling transport unit, and a signaling gateway control unit (58). The protocol interlace unit converts signaling information between a first format and a second format and exchanges signaling information in the second format with a user access element, such as a digital loop carrier (26), ol the signaling network (10). The protocol interlace unit may include any number ol individual protocol interlace units such as an ISDN protocol interlace unit (50), a luture protocol interlace unit (52), a TAPI/TSAPI protocol interlace unit (54), and an SS7 protocol interlace unit (56). The signaling transport unit performs link speed conversion on the signaling information in the first format so that the signaling information may be exchanged with a transport signaling link, such as a link (15), ol the signaling network (10) at a desired rate. The signaling transport unit may include any number ol individual signaling transport units such as an SS7 signaling transport unit (68) and an SS7/ATM signaling transport unit (70). The signaling gateway control unit (58) controls an exchange ol signaling information in the first format between the signaling transport unit and the protocol interlace unit.
43 Claims, 2 Drawing Sheets
SIGNALING NETWORK GATEWAY DEVICE
AND METHOD FOR USE IN A SIGNALING
TECHNICAL FIELD OF THE INVENTION 5
This invention relates generally to the field of telecommunications and more particularly to a signaling network gateway device and method for use in a signaling network such as a Signaling System 7 network. ^
BACKGROUND OF THE INVENTION
Signaling in a telecommunications network is the act of transferring signals or signaling information pertaining to call management and processing. Signaling is simply the 15 information exchanged between switching nodes or signaling transfer points and may be used to perform four basic functions: supervising, alerting, addressing, and billing. Supervising involves monitoring the status of a line or circuit to see if it is busy, idle, or requesting service. In an 20 automated telecommunications network, supervisory signaling information is provided to reflect or direct the status of a line or a circuit such as the on-hook/off-hook status. Alerting or notifying involves providing signaling information indicating the arrival of an incoming call at the end 25 user's telephone device. Addressing involves providing address signaling information indicating the address of a calling party, a called party, or a telecommunications network element. The address signaling information is used for transmitting routing and destination signals over the net- 30 work. Billing involves providing signaling information to properly bill a call such as by providing information regarding the billing number, the duration of a call, and the level of service.
In most telecommunications applications, the user pro- 35 vides signaling information along with the voice or data signal and the signaling is thus referred to as in-band signaling. In-band signaling is primarily provided using multi-frequency and single frequency signals that are provided along with the voice or data signal in the same circuit. 40 For example, in-band signaling may include the use of tones which pass within the voice frequency band and are carried along the same circuit as the talk path that is being established by the signaling information. In-band signaling suffers several disadvantages such as a reduction in available 45 bandwidth for transmitting information because of the presence of the signaling information. Another disadvantage includes the use of full bandwidth channels to provide signaling information that requires only a fraction of this bandwidth in many situations. In-band signaling also 50 increases the accessability of sensitive information such as billing, addressing, and monitoring information which increases the opportunity for fraud. Further disadvantages of in-band signaling includes relatively slow performance when setting up and disconnecting circuits. 55
As a result of these and other disadvantages, a completely separate signaling network was developed that is dedicated to providing signaling information separately from the channel or circuit carrying the content such as voice or data information. This may be referred to as out-of-band signal- 60 ing and has been implemented, primarily, to provide interoffice signaling. Out-of-band signaling increases the overall network bandwidth and allows for more sophisticated telecommunications services to be provided because of the added flexibility of providing content through one network 65 and signaling through another. For example, signaling information may be exchanged over the signaling network
between an originating switching system and a destination switching system before a content or traffic circuit is established to determine if the called station is busy. If busy, a content circuit or channel is not established allowing it to be used for another call.
Out-of-band signaling was first implemented using common channel interoffice signaling (CCIS) for transmitting signaling information for a group of trunks over a separate channel. CCIS uses packet switches in its signaling network that may be referred to as signal transfer points (STPs). Today, signaling networks are using a newer out-of-band signaling system and protocol developed by the International Telegraph and Telephone Consultative Committee (CCITT) which is called Signaling System 7 (SS7). SS7 uses an out-of-band signaling protocol that may be implemented in digital signaling networks. SS7 provides a layered functional structure and uses destination routing, octet oriented fields, variable length messages, and a highly reliable message transfer protocol. SS7 also provides flow control, connection and connection-less services, and Integrated Services Digital Network (ISDN) capabilities. Out-of-band signaling solves many of the disadvantages associated with in-band signaling.
A typical out-of-band signaling network will include a local digital switch, transmission facilities with associated transport devices including a first channel bank and a second channel bank, an STP, and a service control point (SCP). The STP may be implemented as a specialized packet switch optimized for SS7 packets. The SCP may be used to control an associated local digital switch, or a tandem switch in other embodiments, that supports intelligent network services. In such a case, the local digital switch may be referred to as a service switching point (SSP). The local digital switch and the first channel bank may be employed at a local central office, and the first channel bank may be coupled to the second channel bank located at a second location through a high-speed transmission facility so that signaling information may be exchanged in both directions. The second channel bank may couple to the STP which then couples to the SCP also located at the second location. The second location may be provided anywhere such as another central office, a tandem switch office, or an inter-exchange carriers tandem switch office. The local digital switch receives line and address signaling information from users through subscriber loops and interfaces such as digital subscriber loops, loop carrier systems, and digital crossconnect switches. The local digital switch then provides the signaling information to the first channel bank where it is sent to the STP through network transmission facilities and the second channel bank. The channel banks serve as transmission systems that condition the signaling information so that it may be transmitted across a high-speed network transmission facilities between two network office locations.
In such a signaling network, signaling information may be exchanged in both directions. For example, signaling information may be received at the local digital switch and provided to the first channel bank. The first channel bank serves as a transmission system to condition the signaling information for transport on a high-speed circuit, such as a T-l circuit, so that the information may be provided to the second channel bank at the second location. For example, the signaling information may be provided at a digital signal, level zero (DSO) rate and is then combined into a digital signal, level one (DS1) rate for transmission on the highspeed transport facility. The second channel bank also serves as a transmission system and terminates the high-speed