US 6327258 Method and apparatus for routing internet calls

ABSTRACT – A telecommunications network (10) includes a public switched telephone network (12) and an Internet data network (14). The Internet data network (14) includes an Internet routing element (24) and a line access switch (26). The Internet routing element (24) is coupled to end office switches (16) and local switches (18) of the public switched telephone network (12) by modem trunks (30). The modem trunks (30) provide the Internet routing element (24) with Internet calls re-routed from the public switched telephone network (12) to prevent the Internet calls from congesting trunks (22) of the public switched telephone network (12). The Internet calls are received at an ATM multiplexer (58) within the Internet routing element (24). The ATM multiplexer (58) includes a pool of modems (60) that converts the analog signal on the modem trunks (30) into digital data. The ATM multiplexer (58) includes an ATM cell adaptation unit (66) that converts the digital data into ATM cells for transmission to an Internet Service Provider (42) over an ATM network (48). The ATM multiplexer (58) generates addressing information for the ATM cells through interworkings with signaling protocols of Internet calls. The line access switch includes a similar ATM multiplexer (94) to re-route Internet calls prior to entering the public switched telephone network (12).


The present invention relates in general to telecommunications signal processing and more particularly to a method and apparatus for routing Internet calls.


As access demand on the Internet or with on-line services grows, a proportional increase in the stress on telecommunications equipment occurs to support the access demand. Subscribers typically access the Internet through one or more Internet Service Providers. Each Internet Service Provider is generally accessed by subscribers using discrete local telephone numbers that provide broad coverage into a public switched telephone network. Access to the Internet Service Provider is typically a free local call where the local exchange carrier receives no revenues for the telephone usage. Internet Service Providers terminate in end offices of the public switched telephone network using conventional subscriber numbering plans. No control exists as to Internet subscriptions, local telephone number assignments for Internet Service Providers, or locations of Internet Service Providers. Internet traffic between subscribers and Internet Service Providers is mainly routed through the existing public switched telephone network over the same trunks that carry voice, facsimile, and data calls.

Traditional network engineering traffic guidelines do not take into consideration the longer than average hold times of Internet calls. Most telecommunications equipment were designed based on an average call holding time of three to five minutes. However, average call holding times for Internet calls is significantly longer. Current estimates are that Internet and similar services have raised the total average call holding time to over ten minutes. This is expected to increase as the Internet continues to grow. Current end office switches within the public switched telephone network are not configured to support extended access to the Internet. The increased average call holding times of Internet calls place a strain on the public switched telephone network that affects the quality of service provided to and expected by the local subscriber. The public switched telephone network is no longer able to provide effective universal services to its customers while meeting the growing Internet demands.

Increased average call holding times decrease the carrying capacity of trunks and, because the calls are typically free, decrease toll call revenue per trunk as a result of the increased content per call. Though additional trunks may be installed to support the increase in call holding times, such additions increase trunk group costs and operating expenses. Congestion occurs within the public switched telephone network as customers attempt and re-attempt their calls. Service quality suffers resulting in increased customer dissatisfaction and increased service costs. Expensive and complex switch reconfigurations would be needed in order to relieve the congestion on the public switched telephone network caused by Internet calls. Therefore, it is desirable to reduce the congestion in the public switched telephone network caused by the long holding times of Internet calls.


From the foregoing, it may be appreciated that a need has arisen for a technique of avoiding congestion on a public switched telephone network caused by the long hold times of Internet calls. In accordance with the present invention, a method and apparatus of routing Internet calls are provided that substantially eliminate or reduce disadvantages and problems associated with conventional processing of Internet calls.

According to an embodiment of the present invention, there is provided an apparatus for routing Internet calls that includes a pool of modems to convert the analog signals of Internet calls re-routed from a public switched telephone network into a digital data format. An ATM cell adaptation unit converts the digital data format into ATM cells. A network interface transports the ATM cells to an Internet Service Provider over an ATM network separate from the public switched telephone network. The ATM cells for the Internet calls include addressing information generated by an ATM addressing unit in conjunction with the signaling protocols of an SS-7 network for determining the appropriate destination of the Internet calls.

The present invention provides various technical advantages over conventional Internet call processing. For example, one technical advantage is to re-route Internet calls off of the public switched telephone network. Another technical advantage is to avoid placing Internet calls onto the public switched telephone network. Yet another technical advantage is to transport Internet calls in asynchronous transfer mode cell format over an asynchronous transfer mode network to an Internet Service Provider. Other technical advantages are readily apparent to one skilled in the art from the following figures, descriptions, and claims.


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