Smart solutions to VoIP questions
E1 E1 is an ITU-T standard that defines the basic protocol and structure for transmission of TDM data over a physical circuit (most often the physical connections use twisted pairs and conform to G.703). It is widely used in Europe. An E1 primary rate trunk has a total of 32 time slots allocated within each frame of data. … Read more
TDM Stands for: Time Division Multiplexed This is one method by which multiple streams of data are combined together into a single stream of data for transmission down a cable or optical fibre. The combined streams may then be separated out again into individual streams at the far end of the cable as required. When … Read more
Getting more advanced In part 2, we looked at several ways in which an Asterisk system administrator can help to make their system more secure, with special emphasis on avoidance of toll fraud. In this, the third and final article in the series, I will pick up on a topic that was left unfinished at the … Read more
Protecting your Asterisk server In part 1, we examined the techniques that are used to probe for vulnerabilities in a SIP server and reviewed the types of exploitation a would-be hacker hopes to use. In this second part, I look at the ways you can protect your Asterisk or other SIP server and guard against weaknesses … Read more
A growing problem Like a slice of Victoria sponge cake on a summers day attracts wasps, so new technologies seem to attract the attention of cyber-criminals. The more widely used the technology, the greater the interest. It was inevitable, and widely predicted, that VoIP would become a favorite target for hackers as its popularity and uptake increased … Read more
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
Manufacturers different naming conventions While SIP is an industry standard protocol, the names assigned to the configuration fields on an IP phone are far from standardised. The tables below show the text labels that you can expect to see on the web interface configuration forms next to the boxes where you must enter your settings. … Read more
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
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
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