Voice services represent the largest revenue potential for carriers worldwide, and IP network traffic is growing faster than any other type. So, combining the two makes sense for providers building profitable networks for the future.
Alcatel understands the successful deployment of Next Generation Networks depends on the seamless mediation between the TDM world and the packet world. In order for the carrier to succeed with IP Telephony, they must satisfy just one customer requirement: make IP Telephony behave just like the public switched telephone network (PSTN), or better.
IP Telephony must deliver the same toll-quality voice, the same rapid call set-up, the same reliability, and the same universal connectivity as the PSTN. It must also support all the "intelligent" services of the PSTN, including call forwarding, call waiting, toll-free numbers, and so on.
But that`s not enough; IP Telephony must surpass the PSTN. Otherwise, why would users bother to switch? In the end, value-added services and advanced capabilities will determine the success or failure of IP Telephony. The following figure shows an overview of Alcatel`s comprehensive solution:
The Data Network incorporates two major components to provide enhanced services and connection to users, the SoftSwitch and Gateways.
The SoftSwitch brings all the value-added services, typical in a voice network, to any type of voice or multimedia call. Intelligence in the SoftSwitch controls the Gateways and interworking for call signaling toward the PSTN. At the same time, it acts as a gateway to the intelligent network environment providing access to even the most advanced tailor-made services.
In the data (IP and ATM - for Quality of Service) world many different standardisation bodies are competing with one another, and this can be rather confusing for the customer. Alcatel is compelled to support many different protocols in this architecture to guarantee the openness of the solution (such as e.g.
MGCP/MEGACOP and SIP).
Gateways allow voice calls to be transported over a data network. Depending on their location in the network, there are different types of gateways.
* Residential gateways - RGW are directly connected to Customer Premises Equipment - CPE (POTS, ISDN phone set, PC phone.) they allow the transport of voice calls originating from individual residential users directly over a data network. Typically a Residential Gateway will be placed at the customer`s premises and will terminate a limited number of phone sets (1 to 10).
* Access gateways - AGW have the same functionality as residential gateways, but have a greater capacity. Typically, they will terminate a few hundreds of either residential or business subscribers and are therefore placed in the network. Alternatively, an Access Gateway can be connected to a (multi-service) access node.
* Corporate gateways - CGW are placed at the CPE to connect a (conventional) Private Automatic Branch Exchange (PABX) to the data network: they allow the transport of voice calls originating from many users of a corporate network to a data network.
* Wireless gateways have the same function as access gateways but for mobile access networks.
* Trunking gateways - TGW connect voice switches to the data network. The TGW works in conjunction with the SoftSwitch products and internationally proven SS7 network components to offer end-to-end next generation network solutions.
Clearly, IP applications offer one of the most attractive - but challenging - fields for network operators. A field which requires interworking with service providers and software developers to create value-added services and advanced capabilities
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