There are two basic techniques. The first is to use the telephone network to get you all the way home. Dialing back to the office using normal long distance is one of the most expensive ways of staying connected, but it has simplicity on its side. No prior arrangements, no funny software, and no monthly fees. To save money, don't call direct.
Most hotels see long distance as a profit center, and charge exorbitant rates.
Instead, use a telephone credit card to place the call and avoid most hotel charges. A common alternative is to try and get a guest account at an Internet site where you're traveling. This usually works, if you've got the time to track down local postmasters and beg for accounts. But there are no guarantees, and the effort can be substantial. As your time on the road increases, 800-style service can be an alternative.