VoLTE Flows – Basics

I’ve just recently changed my job and that reminded me, what it means to start from the beginning again. To help those of you who have just started with VoLTE/IMS I’ve created a short presentation.

Let me know if it works (and maybe one day I’ll find some to make a recording too 🙂 ). Good luck!

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4G/5G, VoLTE, RCS, IMS, SIP, WebRTC, IoT/M2M Descrition, CallFlows, Illustrated Guides, Tests and other stuff for telco egineers

2 thoughts to “VoLTE Flows – Basics”

  1. Great work Karel. For an enhancement; how’s about adding ‘CHARGING’ to your flows? It’s amazing, in general, how little treatment is given to charging of VoLTE. I guess most people concentrate on the deep technical aspects of getting VoLTE calls established and connected in the IMS network but, when it comes to making sure the money is brought in for VoLTE calls I guess most people expect they will be either ‘free-of-charge’ or part of a ‘flat-rate’ bundle!

    1. Thank you for the comment! You are very right. Charging is often left out though it is very important. It is one of entries on my To-Do list, hope I’ll find some time to write the post.
      In general VoLTE charging may be based on CDR’s generated by EPC and/or IMS nodes. The format and content of the CDR’s for the SGW, PGW, P-CSCF, S-CSCF and the TAS are defined in 3GPP TS 32.298. VoLTE charging architecture for Online and Offline Charging is then defined in 3GPP TS 32.240 and 3GPP TS 32.260.
      In my experience with VoLTE deployments I can say that only very few operators use Rf interface in IMS (offline charging), about 50 % then use Ro or (mainly) Camel from TAS for prepaid. In my belief charging is done mostly in EPC (S8HR – e.g. triggered by S/P-GW) rather than in IMS (LBO – e.g. triggered by TAS).

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