What did the court decide in Henson v. Santander Consumer USA Inc.?
Answered for: US
All that matters is whether the target of the lawsuit regularly seeks to collect debts for its own account or does so for "another."
The Court held that a company collecting debts it purchased for its own account is not for that reason a 'debt collector' under the FDCPA definition at issue. The sentence above is the court in its own words.
This answer is true in US and nowhere else on this site. Another jurisdiction is another answer, or an honest gap: see what has been read for US.