Compared with asterisk and freeswitch, there are a lot of slots. As for how to choose it, the benevolent sees benevolence, and the wise sees wisdom. In my experience, I think the asterisk configuration is relatively simple (I really hate the xml configuration), but freeswitch is relatively high in sound quality and performance. The performance of asterisk1.8 is much better than before, but I'm disappointed that the thread model is much more conservative than freeswitch, especially the thread inserting operations, which is crazy. The stack processing of Asterisk is also a disappointment for me. Under normal circumstances, if there are some exceptions, the performance will be greatly affected. If you want to perform a comparative test, you may want to have a more equitable test solution. For example, if you use the latest version, all the test procedures are the same, and the configuration of the test machine is the same.
The following are some of the links to be collected, both in English and later.
Http://lists.digium.com/pipermail/asterisk-users/2012-February/270100.html
Http://www.freeswitch.org/node/117
Http://www.richappsconsulting.com/blog/blog-detail/asterisk-vs-freeswitch/
Http://anders.com/cms/266
Http://www.zdnet.com/blog/greenfield/open-source-voip-asterisk-or-freeswitch/233
Http://www.dslreports.com/forum/r23246683-FreeSwitch-vs-Asterisk