- SIP load balancing
This product allows you to not worry about problems with growth and scale from the beginning. It has been very reliable as you configure it, then it runs well, and you never really need to touch it once it's setup and working.
Would be nice to have more sample config files for different kinds of scenarios rather then just one default config file.
The server itself does load balancing however the most difficult thing I found was building a fail-over for it.
However, if you want to build a fail-over for it that's the tricky part since most sip traffic is routed using UDP. There are plenty of amazing TCP load balancers out there such as HAProxy but none for UDP. You need to use something like Keepalive and fail-over IP and restart the server on fail-over
This product can scale insanely.
The fact that it can handle hundreds of thousands of subscribers is great and means you won't have to worry about scalability for a very long time.
They just provide the server open source and I don't use them for support.
I previously used Asterisk or Freeswitch to handle registrations and SIP traffic, this is very limited and cannot scale. Kamailio allows you to load balance many Asterisk or Freeswitch servers and move the SIP registration off of the media server allowing for more server resources resulting in more calls per server.
There is a small learning curve, but the hardest part to learn is the configuration syntax which is almost like its own language. Once you get the basics, there are plenty of online tutorials and articles to help you move forward.
A better and stable service with load balancing to allow me to guarantee up-time
leads to happier customers.
Set-up cost was my time it took to do the original installation and configuration.
The main cost with this will be your server hosting costs. I personally run this on a virtual machine on a cloud VPS provider.
I looked at Opensips which is a similar SIP proxy. I prefer Kamailio and feel the community and the updates, as well as the available modules, are better and easier to work with.
Create a virtual machine and try it out. Try out the different features and different modules available. Check out http://kb.asipto.com/asterisk:realtime:kamailio-4.0.x-asterisk-11.3.0-astdb and see how to use Kamailio with Asterisk.