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…

VoIP QoS Settings – part 1

The QoS settings on VoIP phones and related equipment can be perplexing. Here, I will attempt to explain what parameters like CoS, ToS, DiffServ and DSCP really mean and offer practical suggestions for the values that should be assigned to them. Part 1 of this article starts with a broad overview and then focuses on … Read more…

Installing Mediaproxy 2 on CentOS 5 64bit

Mediaproxy 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. Unlike Mediaproxy 1, the new version has a lot of dependencies and it can be quite tricky to … Read more…

Installing OpenSIPS v1.6.1 on CentOS 5 64bit

Smartvox Limited offers a consultancy for installation of OpenSIPS -we have expertise and experience installing and configuring OpenSIPS, Asterisk and PSTN gateways. We also have a wealth of experience in systems integration and networking to get your OpenSIPS server working smoothly with your existing VoIP infrastructure. Details of our consultancy services are located here. However, … Read more…

Asterisk behind NAT

Scenarios in which NAT may adversely affect Asterisk SIP connections The Asterisk Server is behind NAT The Asterisk server could be on the LAN (or in a DMZ) with a NAT firewall between it and the Internet. When it communicates with external peers or devices, the network connections have to pass through the local NAT … Read more…

Using SIP Devices behind NAT

SIP Devices behind NAT: What solutions are available? When an IP phone is installed behind NAT, problems can be created by the NAT device itself, by the phone’s inability to correctly understand its own networking environment or from a combination of the two. Because it is such a common problem, most IP Phones have built-in … Read more…