2 offices/basic internet needs - time to say goodbye?

My internet is 3 Mbps DSL which at best is 2.4 down, 400K up. It is off contract. Bandwidth competes with 2 active computers and other internet appliances. As you can imagine, call reception takes a hit, in fact it's pretty much unusable. Logically the easiest solution is to get better internet.

Here's the rub - I now split time equally in 2 different states and only need basic internet service in both locations.

In looking at landline and voip alternatives, one in particular which grabs my attention is a service offered by most cell providers which connects your current phone (cordless or otherwise) to their CELL network. They provide the box which has an antenna for added reception.

Since it's pulled off my internet network there's no competing for valuable bandwidth, less need to upgrade internet service (at both locales) in supporting voip, it's portable (just bring the phone and box with), business number is retained, outbound caller ID is retained, call clarity improves, and 6 months of paid but unused internet service is avoided since any new internet solution requires a 1 year contract.

In light of my circumstances does anyone have any alternatives I should consider? Thanks.