Having an Open Source software telephone center as Asterisk may have sound a bit experimental a few years ago.
But Open Source software and mentalities tend to change ...

Nowadays, we can recycle pretty much any old computer or router and stransform it into a phone server.
For a small number of users, it's a low cost solution that recycles hardware that still works.

The Asterisk software consumes less mémoire, low disk space and is not very CPU intensive.

Thanks to its API - Asterisk Managment API - we can integrate it with pretty much any CRM software on the market compatible with this technology.
We have ourselves integrated our  Odoo system with our Asterisk server in such a way that when a customer calls with a known phone number, its CRM card opens automatically and a phone call is logged..