Asterisk is an open source and free software implementation of a telephone PBX VoIP solution. Asterisk offers features such as:
=> Voice-over-Internet protocol (VoIP)
=> Voice mail
=> Conference calling
=> Interactive voice response i.e. phone menus
=> Automatic call distribution
=> Custom programming in C or Perl using AGI
From the article:
Voice over Internet Protocol (VoIP) has emerged as a popular technology for modern voice communications. Many organizations have replaced their analog or proprietary digital telephone systems with VoIP-based solutions. This allows the consolidation of telephone services into an existing IP infrastructure. In addition, using IP to host voice services lets the organization leverage existing expertise–while retaining all of the network’s management advantages. Though not without its disadvantages, VoIP provides a compelling option to those looking for a telephone solution.
This article will present a simple VoIP solution using Asterisk, an open source private branch exchange (PBX) product. It will show you how to install Asterisk, configure it using its LDAP backend, and connect to it using the Ekiga software VoIP client and a Cisco 7900 Series VoIP telephone to make calls.
=> Open source telephony: a Fedora-based VoIP server with Asterisk
I've worked with a various load balancing systems (LBS). They are complex pieces of hardware and software. In this post I will highlight some of the open source load balancing software. But what is load balancing?
It is nothing but a technique used to share (spared) load / services between two or more servers. For example, busy e-commerce or bank website uses load balancer to increase reliability, throughput, uptime, response time and better resource utilization. You can use following softwares as an advanced load balancing solution for web, cache, dns, mail, ftp, auth servers, VoIP services etc.
Linux Virtual Server (LVS)
LVS is ultimate open source Linux load sharing and balancing software. You can easily build a high-performance and highly available server for Linux using this software. From the project page:
Virtual server is a highly scalable and highly available server built on a cluster of real servers. The architecture of server cluster is fully transparent to end users, and the users interact with the cluster system as if it were only a single high-performance virtual server.
=> Project Web Site
Red Hat Cluster Suite
It is a high availability cluster software implementation from Linux leader Red Hat. It provide two type services:
- Application / Service Failover - Create n-node server clusters for failover of key applications and services
- IP Load Balancing - Load balance incoming IP network requests across a farm of servers
=> Product web page
The High Availability Linux Project
Linux-HA provides sophisticated high-availability (failover) capabilities on a wide range of platforms, supporting several tens of thousands of mission critical sites.
=> Project web site
Ultra Monkey is a project to create load balanced and highly available network services. For example a cluster of web servers that appear as a single web server to end-users. The service may be for end-users across the world connected via the internet, or for enterprise users connected via an intranet.
Ultra Monkey makes use of the Linux operating system to provide a flexible solution that can be tailored to a wide range of needs. From small clusters of only two nodes to large systems serving thousands of connections per second.
=> Project web site
Personally, I've worked with both LVS and Red Hat Cluster Suite and I highly recommend these softwares.