Question Maybe you can help with

I am an IT manager of a small company of 40 employees. I am going to upgrade our phone systems within the next few months and I would like to know if there is an advantage for me to do this. I could see maybe a large company benefiting from VOIP, but I do not think a small company would really benefit. Let me know what you think. Right now we use 12 of our 24 line T-1 for voice and the other 12 for internet.