I suggest you find time and consult Washington since he is near you i assume, from the posts and personally having dealt with him on afew issues regarding the same he is your best bet for the answers you seek.

 For one to effectively answer you, we need to know exactly what your set up is, what you intend to do and achieve, the location of offices, type of pabx etc. In summary Voip is supposed or will always be cheaper and that also means its likely to have good benefits if implemented the right way according to what your plan is. E1 is equally good just that the initial cost is likely to be higher, the rest depends on your internal controls and budgets.

--
Wagah Hayanga
"...indeed, the forest did change but the monkeys in it remained the same" - PLO.