Which IPPBX is better for this scenario?

Hello,
I need a VoIP server with 10000 extensions and 1000 concurrent call(with echo cancellation). Now which open source IPPBX is the best for this scenario?
Which IPPBX is better for this solution? Asterisk or freeswitch? or kamailio? (if the asterisk is better, Which version of it is the best? LTS Releases or Standard Releases)
Thanks for your replying. With Regards.Mojtaba

The 2 Answers for your questions are pretty obvious due that you are asking in the Asterisk Forums.

1- Asterisk

2- 11.x LTS

Hello,
What is different between Asterisk 11-LTS and Asterisk 1.8-LTS ?
Thanks

The difference between 1.8 and 1.11 is that 1.11 is much more modern and has a lot of new features. I recommend using 1.11, but I have not tested the performance difference between the two versions. If you want to set up such a big deployement, you will have to do that.

I think that such a big system will need a combination of Kamailio and Asterisk boxes. But I am not familiar with such deployements, so I really can not give more advice than that.

[quote=“mespio”]Hello,
What is different between Asterisk 11-LTS and Asterisk 1.8-LTS ?
Thanks[/quote]

read the upgrades svn.digium.com/svn/asterisk/branches/11/