Categories
Software Voice over IP

VoIP is an only child – ‘Gotchas’ on running VoIP applications inside Containers

It’s 2021, and everyone loves Containers; Docker & Kubernetes are changing how software is developed, deployed and scaled. And yet so much of the Telco world still uses bare metal servers and dedicated hardware for processing. So why not use Containers or VMs more for VoIP applications? Disclaimer – When I’m talking VoIP about VoIP […]

Categories
Kamailio Voice over IP

Kamailio Bytes – OnReply Route

So far with most of our discussions about Kamailio we’ve talked about routing the initial SIP request (INVITE, REGISTER, SUBSCRIBE, etc), but SIP is not a one-message protocol, there’s a whole series of SIP messages that go into a SIP Dialog. Sure the call may start with an INVITE, but there’s the 180 RINGING, the […]

Categories
Voice over IP

SIP Hold – With RFC6337

How SIP hold using RFC6336 is implemented and how it looks in production.

Categories
Voice over IP

FreeSWITCH + ESL = Programmable Voice

An overview of FreeSWITCH’s ESL

Categories
EUTRAN IMS / VoLTE LTE Mobile Networks RFCs & Standards SDM Voice over IP

Diameter and SIP: Registration-Termination-Request / Answer

These posts focus on the use of Diameter and SIP in an IMS / VoLTE context, however these practices can be equally applied to other networks. The Registration-Termination Request / Answer allow a Diameter Client (S-CSCF) to indicate to the HSS (Diameter Server) that it is no longer serving that user and the registration has […]

Categories
EPC IMS / VoLTE LTE Mobile Networks RFCs & Standards SDM Voice over IP

Diameter and SIP: User-Authorization-Request/Answer

The Diameter User-Authorization-Request and User-Authorization-Answer commands are used as the first line of authorization of a user and to determine which Serving-CSCF to forward a request to.

Categories
EPC IMS / VoLTE LTE Mobile Networks RFCs & Standards SDM Voice over IP

Diameter and SIP: Server-Assignment-Request/Answer

These posts focus on the use of Diameter and SIP in an IMS / VoLTE context, however these practices can be equally applied to other networks. The Server-Assignment-Request/Answer commands are used so a SIP Server can indicate to a Diameter server that it is serving a subscriber and pull the profile information of the subscriber. […]

Categories
EPC IMS / VoLTE LTE Mobile Networks RFCs & Standards SDM Voice over IP

Diameter and SIP: Location-Info-Request / Answer

These posts focus on the use of Diameter and SIP in an IMS / VoLTE context, however these practices can be equally applied to other networks. The Location-Information-Request/Answer commands are used so a SIP Server query a Diameter to find which P-CSCF a Subscriber is being served by Basics: The RFC’s definition is actually pretty […]

Categories
EPC IMS / VoLTE LTE Mobile Networks RFCs & Standards SDM

Diameter and SIP: Multimedia-Authentication-Request/Answer

These posts focus on the use of Diameter and SIP in an IMS / VoLTE context, however these practices can be equally applied to other networks. The Multimedia-Authentication-Request/Answer commands are used to Authenticate subscribers / UAs using a variety of mechanisms such as straight MD5 and AKAv1-MD5. Basics: When a SIP Server (S-CSCF) receives a […]

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
Voice over IP

Automated SIP testing with sipcmd

Using sipcmd to test SIP Services from the command line

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Kamailio RFCs & Standards Voice over IP

SIP SIMPLE – Instant Messaging with SIP

A look into Instant Messaging using SIP

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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 IMS / VoLTE LTE Mobile Networks 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.

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Kamailio Python Voice over IP

Kamailio Bytes – KEMI Intro

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

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EPC EUTRAN IMS / VoLTE LTE Mobile Networks 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.