We’ve talked a bit in the past few posts about keys, K and all it’s derivatives, such as Kenc, Kint, etc. Each of these is derived from our single secret key K, known only to the HSS and the USIM. To minimise the load on the HSS, the HSS transfers some of the key management … Continue reading LTE (4G) – EUTRAN – Key Distribution and Hierarchy
We’ve already touched on how subscribers are authenticated to the network, how the network is authenticated to subscribers. Those functions are done “in the clear” meaning anyone listening can get a copy of the data transmitted, and responses could be spoofed or faked. To prevent this, we want to ensure the data is ciphered (encrypted) … Continue reading LTE (4G) – Ciphering & Integrity of Messages
How LTE Subscriber authenticate the network
LTE/4G’s use of RAND and K to verify subscribers identity.
Contents of a USIM, fields & their meanings and basics of EUTRAN authentication.
Implementing SCTP in Kamailio
Who is calling?
XKCD said it best: Sometimes standards are created that are superior in some scenarios, and just don’t get enough love. To me Stream Control Transmission Protocol (SCTP) is one of those, and it’s really under-utilised in Voice. Defined by the SIGTRAN working group in 2000 while working to transport SS7 over IP, SCTP takes all … Continue reading SCTP (And why you should be using it)
The rules for which headers to use when creating a SIP request and knowing where to route it.
Using sngrep to view SIP logs like a champ.
SIP Proxy types, such as Stateless & Stateful explained, with examples.
When a final response, like a 200 OK, or a 404, etc, is sent, the receiving party acknowledges that it received this with an ACK. By provisional responses, such as 180 RINGING, are not acknowledged, this means we have no way of knowing for sure if our UAC received the provisional response. The issues start … Continue reading SIP Extensions – 100rel SIP (RFC3262)
Using the Dispatcher Module for load balancing functionality and intelligent dispatching of SIP messages.
Introduction to Encoding & Decoding data in ASN.1 (Using Python)
How the AKAv1-MD5 algorith derives keys and how it’s used in IMS Networks
Workhorse of VoIP / VoLTE / SIP / H.323 / IMS, we take a deep dive into what every bit of RTP means. Pun very much intended.
Explanation of what a SIP Registrar does, Contact header and Address on Record, and how it all fits together to route messages correctly.
SIP Register status, expires and why it’s often misunderstood.
Explanation of Record-Routing, why it exists and how it’s used.
Understanding the SDP protocol and how it’s used to negotiate and setup media sessions.
