Using the Clusterer Module for contact replication

Summary In this, the second part of a three-part article about the Clusterer Module, I explain how I got on when testing a pair of OpenSIPS Registrar Proxies configured as a highly available cluster. The design, which uses Pacemaker to assign a floating IP to the currently active server, is described in some detail in … Read more…

HA Scenarios and the OpenSIPS Clusterer Module

Summary System reliability and avoidance of down-time are themes that recur time and again with Smartvox customers. In this article I will review some of options available to a system designer who wants to build a highly available OpenSIPS solution, paying particular attention to the new Clusterer module which is at the heart of a set … Read more…

Using ClusterLabs Pacemaker with OpenSIPS

Summary In this article we examine how Pacemaker and Corosync might be used to supercharge OpenSIPS and build a highly available clustered solution. The focus is entirely on High Availability rather than any form of load sharing. This means we are looking for a way to have more than one server contactable on the same IP … Read more…

Top reasons why VoIP calls drop

VoIP based phone systems bring many benefits, but they also bring some problems. Not least is the annoying tendency for some calls to drop mid-way through your conversation for no obvious reason. In this article I will identify the most common reasons why a VoIP call might suddenly drop mid-way through an established call and explain … Read more…

Pika µFirewall SIP firewall review

A new way to secure your IP-PBX Recently introduced by the well-established Canadian telecoms manufacturer Pika Technologies, the Pika µFirewall offers a novel way to make your Asterisk (or any other SIP-based PBX) more secure. The best way to describe it is as a “SIP Firewall”, but unlike conventional network firewalls, installation is very simple … Read more…

SIP User Credentials in the ITSP environment – part 3

In this, the third part of the article, we will look at how the ITSP Proxy server handles outbound calls, paying particular attention to the authentication requirements and to the handling of Caller ID. You may also wish to refer back to part 1 where we reviewed the basic entities and concepts used to identify … Read more…

SIP User Credentials in the ITSP environment – part 2

In part 1 of this article we reviewed the basic entities and concepts used to identify a user, a handset or service. It discussed in detail how these entities are used to register devices, either simple single-line devices or SIP trunks. Now, in part 2, we will examine in more detail the handling of inbound … Read more…

SIP User Credentials in the ITSP environment – part 1

This three-part article reviews the SIP entities that identify a user, a handset or service and looks at how they are used to register devices, authenticate and identify users and route calls. The subtle differences in the use of these entities can be confusing, even to an experienced SIP technician. Handling of the entities in … Read more…

RTP, Jitter and audio quality in VoIP

In this article we will briefly look at what RTP is and how it is used to stream VoIP audio. The article then considers how certain network transmission characteristics may introduce jitter or packet loss and the measures that are used in VoIP equipment to mitigate the effects. Other phenomenon which have a bearing on … Read more…