T-1 Alternative

I would like some information on t-1 alternatives. We currently have 4 t-1’s and it is very expensive. I am looking for a few ideas for an alternative method. All current t-1’s span close to 100 miles each and i am in a rural area so my options are going to be limited.
I have been doing some research on microwave, but that seems to be as much or more than the t-1’s we have in place now.
If anyone has any ideas that would be more cost effective i would greatly appreciate it!!
Has to be reliable/security is a must.
Cheers
Sitizn Willie