With all this talk of 5G and now 6G, it’s sobering to think that the majority of roaming agreements today use 2G/3G and CAMEL for all the realtime charging.
So what is CAMEL and how does it work for charging mobile subscribers?
CAMEL handles charging in 2G and 3G networks, much like Diameter handles charging in LTE.
CAMEL runs on top of SS7, specifically it sits on top of TCAP, which sits on top of SCCP, which can ride on M3UA or MTP3 (so it sits at the same layer as MAP).
CAMEL is primarily focused on charging for Voice & SMS services, as data generally uses Diameter, so it’s voice and SMS we’ll focus on.
CAMEL is spoken between the MSC (gsmSSF) and the OCS (gsmSCF).
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Ahhh, this post brought back some good memories! My first ever real job was admin and maintenance of a Siemens prepaid and hosted PBX IN system based on CAMEL (and INAP, but it went away eventually).
I still have my well worn copy of “CAMEL Intelligent Networks for the GSM, GPRS and UMTS Network” on my shelf. For pure nostalgia reasons!
We even used CAP4 to make some pretty cool services for the pbx. I can still picture the BCSM layout in my minds eye.
Legacy does indeed have a long tail… especially in telecom 
Yes Camel is a brilliant protocol.Its fast its precise and efficient compared to diameter.I agree with the post currently most of the roaming networks are heavily reliant on Camel not only for charging but for mobility as well.But at the moment Volte Roaming is getting deployed faster than ever.Advantage of Volte roaming is every call from home subscriber even while visiting a foreign PLMN will land and home TAS that will elliminated the requirement of TAP CDRs which is a huge plus.And Volte roaming have its own pain points too.for an example Since now all the callls landing on your TAS translation table of TAS should get extremly enlarge Outbound Roamer dialling VPLMN emergency calls might have a hit since now call is routed from home network.Thank you
