The 411 on VoIP Islands

by Jackson Weber

Legacy telephone systems ruled the world of telecommunications until a decade ago. With the advent of Internet, the transition from legacy telephone systems to IP based phone systems became the norm. VoIP (Voice Over Internet Protocol) PBX boxes began replacing legacy PBX boxes in many places. An isolated PBX box using VoIP technology is generally referred as a VOIP PBX. These IP based PBX boxes were practically isolated from other VoIP systems, hence the name VoIP Islands. A VoIP Island lives within a company’s local area network (LAN). VoIP Islands provided lower costs compared to traditional PBX systems.


VoIP Islands and Inter-Connectivity


The VoIP Islands primarily provided voice-based services. This resulted in connecting VoIP Islands to PSTNs (Public Switched Telephone Networks) instead of connecting to other VoIP systems. Telephone companies used technologies such as H323 and H248 to accomplish this connection. The VoIP systems communicated with the outside world of TDMs (Time Division Multiplexing, a method of putting multiple data streams in a single signal) using an internal gateway. This means the packet creation happened inside the company’s network, resulting in VoIP Islands. When VoIP was in its early stages, the preferred approach was to use the VoIP inside a local area network. The process still used PSTN for all outside communications. This resulted in higher costs for the customer. However, the cost of using an IP based system was still lower compared to traditional phone systems. The net effect was an isolated VoIP or a VoIP Island.


Session Initiation Protocol and VoIP Islands


More recently, the SIP (Session Initiation Protocol) was introduced for real time Internet based communications. It was initially used for telephone systems. SIPs facilitated the communication between VoIP systems and PSTNs. VoIP conversion happened within the local area network with the help of SIPs. The VoIP Islands presented a problem with SIPs. SIPs are capable of doing more, not just act as the middleman between VoIP Islands and PSTNs. SIPs could add value in terms of providing voice, data, video, fax and other features of an Internet based communication system.


Evolution of SIP Technology


The evolution started when the technology was used to combine data and voice over an IP network. This resulted in connecting VoIP Islands to other IP networks, not just to PSTNs. This was a great boost to companies building IP based products and services. This meant IT departments could leverage the power of IP based systems to provide a full fledged solution to the whole company, instead of the limited telephony service offered by VoIP Islands. There are many advantages in connecting VoIP Islands using SIP technology. Specifically, the process connects many VoIP Islands using SIP trunking. This adds increased capabilities to a company’s VoIP Islands. SIP trunking allows a company to offer various solutions via VoIP Islands such as voice, video, chat and file transfers. The ROI for using SIP trunking to link VoIP Islands is substantial for many small and medium sized corporations. SIP trunking allows the creation of cost effective switching centers connecting many different VoIP Islands. The elements of using SIP trunking include a telephone service provider, IP PBX, and a gateway between the provider and the IP PBX. The successful implementation of SIP trunking allows the streaming of data, video, voice and other IP services via a single line. This implementation allows customers to use services such as long distance calling, local calling, emails, text messages, directory services, emergency calls and Internet access.


WAN and VoIP Islands


It is clear that VoIP brings huge benefits starting with reliable services. However, if the VoIP Islands are situated in different locations, it effectively minimizes the output from a complex system with connected VoIP boxes. The existing PBX systems can be interconnected using WAN (wide area networks). This allows connecting the central PBX located in the headquarters with other PBX systems located in other geographical locations. When we use traditional trunks to link VoIP Islands, it makes the process inefficient, and offers less ROI on the company’s infrastructure. A gateway can be used to share the PBX located in a corporate head office with various branch offices. Sometimes, traditional PSTNs are used as back-ups in case of a failure in the WAN network. Gateways are placed on either side of the WAN. These gateways essentially communicate over the WAN, and acts as gatekeepers in sending and receiving data.


Optimization of Services


WAN optimization tools can be used in conjunction with gateways to optimize the throughput and performance of connected VoIP Islands. WAN optimization attempts to fill the pipe when data is transmitted via wide area networks. Many vendors use the QOS (Quality of Service) boosting mechanism to improve performance. QOS reduces noise from other applications. It compresses data and use caching techniques to optimize the use of available bandwidth. The compression of VoIP headers also helps to improve the performance of networks. Services such as QOS allow vendors to setup policy-based transmissions. QOS also helps with the measurement of transmission rates and error occurrences. It also controls the transmission rates to some extent. This is especially helpful when sending high bandwidth data such as video and graphics. Public networks are unable to transmit high bandwidth data reliably without the use of services such as QOS. The output from QOS can be improved by using queuing and packet prioritization techniques. Auxiliary services such as QOS help the efficient and cost effective interlinking of VoIP Islands.


Changing Landscapes


The replacement of public switched telephone networks (PSTNs) with VoIP technology is happening sooner than expected. This is primarily driven by the proliferation of broadband capabilities. Today, most telecom providers are converting their systems to use SIP technology and IP based services. This will accelerate the replacement of traditional PSTNs with VoIP based systems. It will help telecom providers to offer the necessary infrastructure and supply richer Internet experiences to the end customers. In this wave of innovative IP based services, the use of VoIP Islands will be redefined to provide services and capabilities that were unheard of in the past. VoIP peering with the help of SIP systems are becoming more common among telephone and Internet providers in several countries.




Gone are the days when VoIP systems remained isolated in a department or office. Today, VoIP Islands are interconnected to provide powerful user experiences. This trend will continue into the future. It will result in the replacement of plain old telephone systems (POTS) with interconnected VoIP Islands. The end result will be a world of unlimited bandwidth, and unparalleled performance to deliver data, voice, messages, text, files, music, video and graphics from any corner of the globe to another.

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