What killed the trend? Did everyone deploy it and this was it? No, there were many deploying pre-IMS, half-IMS or IMS-ready solutions (most of them being just some re-labeled existing system by the marketing/sales departments of some vendors) for astonishing amount of money, bringing back to them no other benefit that a SIP server with registrar, location and proxy services could deliver.
Many of us, including me, I was reticent about IMS. It was not because things like being a bad idea, but seeing who is behind the movement (read old telco vendors), organizations with few understanding of new communication demands over IP. They couldn't have it pushed beyond voice. Remember, IMS concept promised a framework to offer voice and new real time applications to mobile networks.
But voice was there, it had a dedicated channel (no IP) even in 3G networks. So an IMS with nothing more than voice brought zero add-value to services. There was no real return of investment for most of those deploying x-IMS.
Things are changing, demands for data over mobile networks is increasing, the operators are forced to go to 4G or what so ever will be next. Here we talk about technologies like LTE. With such technologies, there is no longer a dedicated channel for voice. Everything is IP.
Therefore the operators need a system that has to route the voice over LTE. One of the options, the natural one, is IMS.
IMS is a lot about defining standard interfaces, to handle services such as: interconnect, roaming, billing, access policies a.s.o. Not bad at all. Many concepts map directly, entirely or partially, over the standard SIP concepts, e.g., HSS (Home Subscriber Server) and SIP Registrar/Location Server.
It is almost mid of 2011, for few years there was a gap in (public and high) interest regarding IMS. But now is different. Starting with the end of last year, more and more people showed real interest in bringing IMS extensions in Kamailio. They are in the source code repository for some time, still under heavy work, but you can run it -- see the tutorial pointed at this web page.
First the big advantage for companies looking to use it is trying it at very low cost. Although the IMS extensions were available for some long time for free through OpenIMSCore project (which is part of our SIP-Router.org development eco-system), this time there are made available on top of a very stable VoIP/Telephony engine. All the IMS extensions are modules, so the stability of the other extensions and core is not affected at all.
More over, apart of voice, Kamailio (being the core of the IMS solution) offers add-on services such as presence and instant messaging out of the box. Furthermore, existing embedded programming language interfaces to Lua, Perl or Python offer a straightforwards and easy way to implement RTC goodies (e.g., see some slides with a tutorial for sending notifications to Twitter on missed calls).
I summary, with the IMS extensions on top of Kamailio:
- free-as-in-beer system that anyone can try before deciding to pay integrators for professional installation
- rock solid underneath system
- access to other hundreds of RTC extensions
- services beyond voice
- embedded scripting languages
- open source, vendor-unlocked environment, with many companies able to offer professional consultancy services
First part of writing about technologies striking back in VoIP was about IPv6. Same like there, things seems to get serious now (repeating the disclaimer from first part: the statements are made based on the activity inside our mailing lists, looking back at the discussions about these subjects in the past 10 years).
On our mailing list, Jason Penton (new developer to work on IMS extensions), revealed his company plans to deploy IMS in several countries across Africa (Uganda, Tanzania, Nigeria & DRC -- click to see the message).
The development of the IMS extensions is coordinated by Carsten Bock, long time developer and member of management team of Kamailio.
If you are interested in IMS, Carsten (along with other developers) will be present at Kamailio booth during LinuxTag 2011, in Berlin. We will be glad to talk with you, just drop by. We have several visitor passes that we can give away, write me an email if you are interested. Of course, flyers and giveaways will be on site, more details about developers availability at: