Author: John
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HA Scenarios and the OpenSIPS Clusterer Module
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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 of new tools introduced in version 2. The focus of my attention for the Clusterer module is to see if it…
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Using ClusterLabs Pacemaker with OpenSIPS
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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 address. The starting point is assumed to be a pair of similar or identical servers connected on the same subnet, each…
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Using TLS in OpenSIPS v2.2.x
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Using TLS with OpenSIPS: Why do we need it and how is it configured? While support for TLS existed in version 1, the configuration changed significantly in version 2. This article briefly covers the new v2 setup. The role of TLS in VoIP calls Today, it is common practice to use encrypted communication over the Internet whenever possible. The most familiar example is https which provides secure, encrypted web browser sessions for things like online banking…
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Top reasons why VoIP calls drop
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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 how you can diagnose the cause. At the end are some pointers to the solutions for these problems. This article is…
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SIP User Credentials in the ITSP environment – part 3
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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 a user, a handset or service and how these entities are used to register devices. The same entities are also used…
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SIP User Credentials in the ITSP environment – part 2
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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 calls, particularly in the context of using OpenSIPS as an ITSP front end server. Part 3 will look at handling of…
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SIP User Credentials in the ITSP environment – part 1
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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 a live ITSP environment, especially when dealing with a mix of simple single-line devices alongside multi-channel SIP trunks, is quite challenging.…
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RTP, Jitter and audio quality in VoIP
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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 the audio quality on VoIP calls, along with the features used on VoIP equipment to overcome them, are also briefly discussed.…
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How to install Mediaproxy 2.5.2 on CentOS 6 64 bit
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Mediaproxy 2.5.2 is a Python application from AG-Projects which is available as a free download as well as being available as a commercial product from AG-Projects. It is used in combination with the Mediaproxy module of OpenSIPS. Mediaproxy 2 has several dependencies and can be quite tricky to install. The INSTALL instructions that come with the package are very helpful, but unfortunately they are aimed primarily at installers who either have Debian or Ubuntu Linux distributions.…
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OpenSIPS vs Asterisk
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OpenSIPS and Asterisk are both open source projects and both are used for Voice over IP. However, they perform quite different roles, have different capabilities and different strengths and weaknesses. This article reviews how they are so different and considers what role each product can play in the infrastructure of an Internet Telephony Service Provider solution. Fundamental differences A succinct, but slightly technical, distinction between OpenSIPS and Asterisk is that OpenSIPS is essentially a SIP Proxy Server…
