Hello! I have make similar system, in PHP, ina client detail view, the attendent click in the telephone number of client, and the system, dial to the attendent by extension, and complete the call to the client.
The attendent just click 2 dial. With asterisk is possible to record the call to. And in this system, this call add in the call history on client.
If you need more information, please contact me.
Thank you.