Author: John Quick
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Caller ID in SIP
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Equipment receiving calls, whether a humble handset or a sophisticated Call centre ACD system, likes to know the identity of the caller. It may simply display the caller’s number on an LCD display, look it up in a directory so the caller’s name can be displayed or pre-populate a screen with information about the caller […]
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Interrupt Timer for UNO WiFi Rev2 and other ATmega4809 units
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The usual interrupt timer libraries and examples may not work on the Arduino UNO WiFi Rev2 and Nano Every because they use the ATmega4809 processor. So here is a quick and simple example showing how to use one of the inbuilt timers (TCB0) to toggle a variable that can be checked in the loop routine. […]
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Testing the NRF24L01 with Arduino Nano 33
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Summary NRF24L01 modules, because of their low cost, are an appealing option for data transmission over modest distances. They are best suited to unobstructed “line-of-sight” transmission, but one might hope at least to reach an adjacent room indoors. Here, I describe my experience testing a pair of NRF24L01 modules, each linked to an Arduino Nano […]
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Creating and Using Post Templates
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Summary: Using the Full Site Editor, how do you create new templates for use with some or all of your WordPress posts? How do you associate one – or many – posts with a particular template? Which template is used by default when you create a new post? While not a definitive guide, you’ll find […]
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Making OpenSIPS work as MS Teams SBC
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Introduction Alexey Vasilyev posted an article to the OpenSIPS blog site in September 2019 which explained how to use OpenSIPS as an SBC for Microsoft Teams Direct Routing: OpenSIPS as MS Teams SBC – Drops of wisdom, knowledge and news from OpenSIPS I am sure the OpenSIPS community is grateful to Alexey for sharing his […]
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SIP transport protocol transcoding in OpenSIPS
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Introduction This is the final article in my series about fixing SIP header addresses. It broadly overlaps with the theme of the earlier articles. As a VoIP solutions designer, you may want your proxy server to deliberately transcode between different transport protocols. For example, WebRTC to TCP or TLS to UDP. This is possible with […]
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Fixing SIP header addresses – Contact headers
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Part 3 of this series of articles focusses on the Contact header. In particular, I examine the use-cases where it is necessary to “fix” (or alter) a received Contact header. Contact headers work in close combination with Record-Route and Route headers in a mechanism known as loose routing. To get the most from this article […]
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Fixing SIP header addresses – Via headers
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In part 2, Via headers are put under the microscope. I examine how the address in the Via header is set by each node in the path; how and why it may differ from the source address. I will look at the functions available in OpenSIPS to detect and handle situations where the address in […]
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Fixing SIP header addresses – Introduction
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The main theme I explore in these articles is when and how a SIP Proxy should alter (or “fix”) embedded sender address information – IP and port – in a SIP request that it has received. The headers that are most relevant here are Via, Contact and Record-Route
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Contact and Record-Route headers explained
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Diagnosing some problems in the world of VoIP requires close inspection of the SIP messages being exchanged, but there are many occasions where a good understanding of loose routing will be invaluable. The headers that underpin loose routing are Contact, Record-Route and Route. In this post, I explain how they work and provide some insight […]
