To do this, you must be equipped with a telephone box that supports the CALLTO and SIP call protocols.
If this is not the case, you can use the additional external software.
If your telephone provider provides you with VOIP telephony, you can connect using the software.
The paid version of the ZOIPER software http://www.zoiper.com/en allows you to take advantage of calls via Simple CRM.
Advantage; it is compatible with Windows, Mac, Linux, iPhone, and Android.