Why Skype is successful
Ever since Skype was released in late 2003, it was used as the final adjudication of communication, because it “just works” for consumers. The reason also is its simplicity: do not need any additional modems, routers, etc. You simply install the program and use it, taking calls and messages.
History of SIP
At the same time, as appeared Skype, appeared Session Initiation Protocol (SIP). But the main problem was (it remains) that users can only talk openly UDP.
The main problem is that it was (and partly still is) that the majority of clients and servers were only able to talk openly UDP. Because of the nature of SIP, which carries Layer-3/4 information in the Layer-7 networking stack (that is, it puts the IP-addresses and ports for signaling and communications in various protocol headers). SIP-connection has massive issues under NAT, so his work without forwarding home routers was impossible. And the people who are far from the art encountered various difficulties.
It became worse when the modem / router started to implement the logic of Application Layer Gateway (ALG) in their devices to overcome the existing problems. However, following the introduction of already creating disturbances, and the interaction between servers and clients becomes even more difficult.
And that’s where the SIP has become really successful, so it at Internet Service Providers (ISP), as an alternative to telephone lines. Currently, almost all the Cable / DSL modems work with SIP, and if possible, you can easily connect your old phone and talk to a special device over the Internet.
Communication is performed via separate channels and directly routed network and does not depend on the normal IP traffic home network. It also allows him to provide excellent voice quality.
SIP one-way road
In connection with a business-driven approach and established (technically, in terms of “it just works”), innovation dramatically stopped with SIP, and he soon became a way to replace the traditional phone lines to the ones based on SIP.
SIR also used by mobile operators to establish communication between various mobile devices.
Interestingly, the SIP ecosystem eventually got the same specification of services that Skype (encrypted signaling and media, instant messaging, friends lists, presence of voice, video sessions and screen sharing, conferencing, etc.). But the problem was that they were working on a new standard, and some of them were too complicated, and thereby suspend the introduction of innovations in this field. It immediately became a question of incompatibility.
Kamailio with innovation in SIP
The main driving force, which provides a reference implementation of an open source server side is Kamailio. There are a number of successful companies that have adopted and implemented a SIP-based services of the project. Platforms Sipwise one – not even the biggest, but they serve hundreds of millions of call minutes per month on the basis of server Kamailio. Over the past year, Kamailio massively evolved from workhorse that just brought a voice in a complex platform that provides a variety of communication services.
Keep in mind the main principle – it should work fine with the server on the one hand, and should be easy and attractive interface with the other hand. With that, the interface should work on a variety of platforms: mobile phones, computers and so on., What is very good at Skype.