By Steve Valentino
In a traditional PSTN, the quality of service of the calls and continuous connection are very dependable; so, in order for people to switch to IP telephony, the same quality considerations must be maintained or excelled. With IP telephony consisting of distributed elements, the entire architecture has to be strategically managed to provide good service while at the same time reducing the overload and maintenance costs.
Voice over Internet Protocol, or VoIP, solutions include components such as end-user devices, PBX, gateways and gatekeepers, IP network and several protocols that take care of the issues and operations of a transaction. When a call is initiated, there are distributed arrays of routers, which manage the call functions such as identification of the destination, maintenance of the connection between the IP and PSTN, billing management, and alerts about the incoming transaction.
In this competitive VoIP market, VoIP solutions must be able to meet needs such as high-speed interface, predictable performance, quality of service and security. These factors drive application development and infrastructure deployment. The routers should be able to handle thousands of calls through increased bandwidth, and they should also match the interface speeds in order to forward the IP packets. The quality of service is maintained in the router by addressing concerns such as exact sequencing of the packets so that the call is clear and meaningful. Security features are to be implemented to prevent hackers from accessing the infrastructure. This is managed by enumerating the routers, which function as gateways and controllers as private addresses, so they are not accessed through the public Internet.
A robust infrastructure deployment is complemented by application development that adheres to various protocols that are mostly governed by International Transmission Union (ITU) and Internet Engineering Task Force (IETF). Several protocols are available, and the necessity of the implementation depends upon the product groups. Signaling System Seven (SS7) is a protocol that manages the establishment and termination of calls. H.323 is a product-based communication protocol that signals the call to the IP network and the end user.
RTP protocols address the concerns of real-time receipt of calls so that the calls arrive in the same sequence. Media Gateway Control protocol coordinates the actions of gateways. Session Initiation Protocol (SIP) handles the setup and tear down of multimedia sessions between speakers.
With a combination of infrastructure and protocol, VoIP solutions enable the customer to establish calls at a fraction of the rate of PSTN lines, while at the same time maintaining quality.