Published on Nov 12, 2015
A gateway is a network element that acts as an entrance point to another network. An access gateway is a gateway between the telephony network and other networks, such as the Internet.
Access mediation supports the arbitration of call control and signaling between individual networks, resources, users, and services. Access mediation is the next evolutionary step for the advanced intelligent network (AIN). With the growing importance of the Internet, access gateways are a critical component of access mediation. This tutorial presents several application scenarios that utilize an access gateway point between the traditional telephone network and the Internet. First, the tutorial will review general background information on access mediation. As part of this overview, specific information on the important components of access gateways will be addressed. Access gateway-application scenarios will also be discussed. Finally, the tutorial will present several elements of network design that are crucial for a network to support an access gateway.
As stated in the tutorial overview, access mediation supports the arbitration of call control and signaling. The key mediation functions to be managed and controlled include privacy, security, message routing, message screening,message parameter screening, bridging and protocol conversion, performance monitoring and protection, error handling, and billing. The goal of access mediation is to enable the interconnection of individual networks.As shown in Figure 1, access mediation can be created with a mediation point in the signaling network.
The networks that are interconnected can be any service provider's wireline, wireless, long-distance, or Internet network. Signaling messages must be able to pass freely within and between these networks. The networks can vary by standards definition, protocol, and vendor or service provider implementation. Even where standards and protocol match, offered services may vary by availability and implementation. Advanced services may be obtained from a network different from the one providing basic service to subscribers. For each of these cases, several issues must be resolved in order to enable the interconnection of the networks.
As an important application area of access mediation, access gateways allow networks based on different signaling protocols to be interconnected. For example, telephone company mergers have created the need to interconnect networks based on different signaling standards. Wireless networks based on GSM must now interconnect with networks based on IS–41. The access gateway provides the protocol conversion needed to interconnect these networks.
In addition, providers are using TCP/IP networks in place of SS7 for certain signaling (see Figure 3). In Figure 3, a TCP/IP–based network interconnects two distant IS–41–based wireless networks. The TCP/IP–based network is used to transport short messages between the two wireless networks. Since the short messages are not time-critical, the TCP/IP network is utilized to interconnect the distant networks which is a cost-efficient solution.