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 […]
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 […]
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.
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. […]
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 […]
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 […]
My first Pull / Merge in the Kamailio project was to fix the IMS P-CSCF config
Lessons learned about setting up VoLTE / IMS Networks at small scale.
How the P-CSCF address is assigned to a UE in Protocol Configuration Options (PCO) during bearer establishment.
The exchange between a UE and P-CSCF to put SIP traffic into IPsec encapsulated payloads.
Viewing the payload of an Encapsulated Security Payload in Wireshark.
Reverse Engineering the Samsung Sysdump app to unlock IMS Debug and TCPdump functions
Unlocking the built in IMS Debugging tool in Samsung’s Sysdump Utility
Robust Header Compression (ROHC) and it’s use for compressing RTP / VoLTE traffic headers.
How the AKAv1-MD5 algorith derives keys and how it’s used in IMS Networks