Slavery was abolished in the British Empire under a ten year plan to allow owners of newly purchased slaves to get their money's worth. Slaves, however, often took to the hills to wait out the ten years.
Indentured servitude is one where the person sells himself into servitude for some set period; someone wanting their passage money to get to America, for instance.
I don't think most of the indentured servants would tell a voluntary story.
Many were put into the system by the courts and anyone who could get paid for providing labor.