Cheap soft modems have a much harder time retraining, and usually just hang up. These are becoming rare and are mostly ISA slot type. Most internal modems are PCI slot type, and are also soft modems. Preferred by most serious modem users, they sit on your desk, have lots of flashing lights, their own power supply, and even more cables to add to the rats nest behind your computer. There are good and bad modems of all types.
Hard modems are best under all conditions.
They will work in virtually all computers from AT s to the latest Pentiums. They are the easiest to set up, the most forgiving of questionable phone lines, and generally preferred overall. Internal or external is a matter of personal preference. Soft modems, under ideal conditions, work as good as hard modems. Of course, ideal conditions are nearly impossible.