Categories
Voice over IP

FreeSWITCH + ESL = Programmable Voice

An overview of FreeSWITCH’s ESL

Categories
RFCs & Standards Voice over IP

SIP Register – Lesser Known Features

Some of the lesser used / utilized features of the SIP REGISTER method.

Categories
Kamailio Voice over IP

Kamailio Bytes – Multiple Kamailio Instances on a Single Box

Running multiple instances of Kamailio on the same server using init.d

Categories
Kamailio Security Voice over IP

Kamailio Bytes – SIP over TLS (SIPS)

Using Transport Layer Security (TLS) to protect SIP traffic from modification / manipulation and guarantee message authenticity.

Categories
EPC EUTRAN Kamailio LTE Mobile Networks RFCs & Standards Voice over IP

Things I wish I knew about setting up private VoLTE Networks

Lessons learned about setting up VoLTE / IMS Networks at small scale.

Categories
EPC EUTRAN LTE Security Voice over IP

VoLTE / IMS – P-CSCF Assignment

How the P-CSCF address is assigned to a UE in Protocol Configuration Options (PCO) during bearer establishment.

Categories
Voice over IP

Automated SIP testing with sipcmd

Using sipcmd to test SIP Services from the command line

Categories
RFCs & Standards Voice over IP

SIP SIMPLE – Instant Messaging with SIP

A look into Instant Messaging using SIP

Categories
Kamailio Voice over IP

Kamailio Bytes – UAC for Remote User Registration to external SIP Server (Originating SIP REGISTER)

Using Kamailio’s UAC module to send outbound SIP REGISTER messages

Categories
Kamailio Voice over IP

Kamailio Bytes – SIP UAC Module to act as a UAC / SIP Client

Using Kamailio UAC module to send a SIP Text Message (MESSAGE) to an administrator when a user dials an emergency services number.

Categories
EPC EUTRAN LTE RFCs & Standards Voice over IP

IMS / VoLTE IPsec on the Gm Interface

The exchange between a UE and P-CSCF to put SIP traffic into IPsec encapsulated payloads.

Categories
Kamailio Python Voice over IP

Kamailio Bytes – KEMI Intro

Using KEMI to write routing logic using languages like Python, Ruby, Lua and JS

Categories
EPC EUTRAN LTE Security Voice over IP

Using Wireshark to peer inside IPsec ESP VoLTE data from the P-CSCF

Viewing the payload of an Encapsulated Security Payload in Wireshark.

Categories
RFCs & Standards Voice over IP

SIP Supported & Require

Function of Supported & Require headers in SIP.

Categories
Kamailio Software Voice over IP

Kamailio Bytes – Dispatcher States

AP, IX, IP & DX – The meaning of Dispatcher states in Kamailio’s Dispatcher module.

Categories
Kamailio Software Voice over IP

Kamailio Bytes – Rewriting SIP Headers (Caller ID Example)

Stateless Kamailio SIP proxy example for changing Caller ID values

Categories
EPC EUTRAN LTE Mobile Networks RFCs & Standards Voice over IP

The case for Header Compression in VoIP/VoLTE

Robust Header Compression (ROHC) and it’s use for compressing RTP / VoLTE traffic headers.

Categories
Kamailio Voice over IP

Load Testing with SIPp

SIPp (a performance testing tool for SIP) to simulate many concurrent calls leading to many concurrent transcoding sessions.

Categories
Kamailio Voice over IP

Kamailio Bytes – DMQ

Using Kamailio’s Distributed Message Queue to share memory data between Kamailio nodes

Categories
Kamailio Voice over IP

Kamailio Bytes – Transaction Module

Some TM (Transaction Module) use cases in Kamailio