PDF of this tutorial
This and the following two modules discuss application scenarios that utilize an access gateway point between the traditional telephone network and the Internet. These modules will show the importance of access gateways in a network service environment where the Internet is becoming as important as the telephony network. As a result, service providers need to partner or integrate the two networks into a single network.
User-Network Interface Scenarios
As discussed in Topic 2, Internet-based Web sites that are associated with telephony applications and services are a potential site for the use of access gateways. In the example in Topic 2, a Web site on the Internet was used as part of the wireless short-message service. This short-message Web site provided a better user interface to the service than that provided by a wireless keypad. In addition, entering text messages on a telephone keypad is more difficult than typing the text on an alphanumeric keyboard. The Web site could also provide access as a message entry point for more short-message senders. Anyone with Internet Web access could enter the mobile subscriber's telephone number and a message at the short-message Web site.
There are many more telephony-based applications and services that could benefit from similar Web sites. For example, the use of the telephone keypad as a user interface is notoriously difficult. As shown in Figure 5, Internet-based Web sites can be provided for services and applications that are located on telephone switches, intelligent network service nodes (IN SNs), IN SCPs, and IN service management systems (SMSs). For example, IN SN–based applications and services often have user-configurable parameters and lists that control the operation of the service based on the needs of the individual subscriber. Specifically, complex personal number or "follow me" services have been implemented on SNs. As part of these services, the subscriber can set up call forwarding control based on multiple telephone numbers and location lists based on time-of-day and day-of-week. These parameters are difficult to input and administer using only the subscriber's telephone keypad, and the addition of Web sites would greatly enhance the usability of the services. Potentially, this could result in more satisfied subscribers and increased subscription to the services. Similar services and applications are located on telephone switches and IN SCPs. In the same manner, these services and applications could benefit from Web-based user interfaces.
Figure 5. User-Network Interface Example
To expand services and applications, Web-based interfaces can be provided for telephony network administration and operations systems. For example, the FCC mandate to open the telephone network to competitive access provides the opportunity for Web sites to act as access points for administration and operations systems. A competitive service provider could gain controlled access to the incumbent provider's IN SMS through a Web interface. In a similar fashion, Web sites can provide controlled access to other administration and operations systems associated with the incumbent's network.
In these scenarios, the access gateway enables the negotiation of varied network protocols, which are needed to access and control telephone network systems. The systems have been acquired from different vendors and deployed over a wide time frame, resulting in a hodgepodge of protocols and control messages. In addition, most of these protocols and control messages are vendor-specific. The access gateway acts as a single point of translation between multiple Web sites and the varied systems of the telephone network.
Telephone Switch Trigger Control Scenario
The ability to control the status of a telephone switch trigger from the Internet will also become increasingly important to the integration of the telephone network and the Internet. In addition, the ability to turn the triggers associated with individual subscribers "on" or "off" will be crucial. This will become more important as customers demand services that require the use of both the telephone network and the Internet. Topic 5 presents a specific example of such a service that uses both the telephone network and the Internet to expand traditional call waiting service. A network diagram of the basic trigger control scenario is shown in Figure 6. In this situation, an Internet-based application can communicate with the access gateway to request a change in the status of a telephone network trigger for a specific subscriber. The access gateway then communicates with the appropriate telephone switch via the SS7 network, altering the status of the trigger.
Figure 6. Telephone Switch Trigger Control
