Some ISPs offer a certain number of dial up minutes a month (or they offer dial up minutes at a discounted rate for subscribers)...I think that might only be DSL but I don't know. It's worth calling the ISP to find out if they offer such a thing.
Also, some ISPs offer movable internet but you need a special modem for that and pay a higher monthly rate and I don't think you can just switch over for your trip and switch back since it involves hardware changes.
Also, some ISPs offer movable internet but you need a special modem for that and pay a higher monthly rate and I don't think you can just switch over for your trip and switch back since it involves hardware changes.