Categories
5G SA EPC LTE Mobile Networks Voice over IP

IMS Routing with iFCs

Peer behind the magic curtain at how IMS networks route your VoLTE and VoNR calls, and how iFC (Initial Filter Criteria) achieve this.

Categories
Mobile Networks Voice over IP

Adding support for AMR Codec in FreeSWITCH

Adding support for AMR Codec in FreeSWITCH

Categories
EPC GSM LTE Mobile Networks RFCs & Standards

The Surprisingly Complicated world of MO SMS in IMS/VoLTE

Since the beginning of time, SIP has used the 2xx responses to confirm all went OK. If you thought sending an SMS in a VoLTE/IMS network would see a 2xx OK response and then that’s the end of it, you’d be wrong. So let’s take a look into sending SMS over VoLTE/IMS networks! So our […]

Categories
EUTRAN LTE Mobile Networks RFCs & Standards 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 LTE Mobile Networks RFCs & Standards 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 LTE Mobile Networks RFCs & Standards 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 LTE Mobile Networks RFCs & Standards 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 LTE Mobile Networks RFCs & Standards

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
EPC Kamailio LTE Software Voice over IP

Kamailio Proxy-CSCF Pull

My first Pull / Merge in the Kamailio project was to fix the IMS P-CSCF config

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
EPC EUTRAN LTE Mobile Networks Python RFCs & Standards Software Voice over IP

PyHSS Update – IMS Cx Support!

An update to PyHSS to support IMS Authentication for VoLTE

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
Security Software

Reverse Engineering Samsung Sysdump Utils to Unlock IMS Debug & TCPdump on Samsung Phones

Reverse Engineering the Samsung Sysdump app to unlock IMS Debug and TCPdump functions

Categories
EPC EUTRAN LTE Mobile Networks Security Software Voice over IP

VoLTE/IMS Debugging on Samsung Handsets using Sysdump & Samsung IMS Logger

Unlocking the built in IMS Debugging tool in Samsung’s Sysdump Utility

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
EPC LTE Mobile Networks Notes RFCs & Standards Security SIM Cards Software Voice over IP

All About IMS Authentication (AKAv1-MD5) in VoLTE Networks

How the AKAv1-MD5 algorith derives keys and how it’s used in IMS Networks