The integration of the VoIP system into Outlook will allow you receiving electronic messages on missed calls, call transfers etc. By click of a mouse on the number you can also call the addressee from whom you missed the call.
Netropolitan Works builds secure VOIP in Thailand Asterisk systems and can do it in a way that makes sense for your business! http://www.NetropolitanWorks.com/VOIP-Thailand-lp.html