Need Info about microwave

I would like some information about microwave.

We currently use t-1 for remote locations all over 100 miles away.
It was mentioned to the CEO that we should check into using microwave towers and that it would be cheaper.
I have NO idea about microwave, other than I thought it was outdated and was used in the 60’s?
Can anyone please give me some insight on this technology.
Cost, reliablity, SECURITY? Something better perhaps?
Thanks
Sitizn Wille