No it is not legal, it is a violation of the FDCPA law!  Debt is a civil matter, not criminal!

http://800notes.com/arts/Jb8EW-eDhQA/harassin ... ou-need-to-know
See Residents post here also:
http://800notes.com/forum/ta-34af6a034ba34b6/unending-collection-calls
Templates of Letters:
http://800notes.com/Phone.aspx/1-319-242-7350

http://www.ftc.gov/os/statutes/fdcpajump.shtm
http://www.consumerfinance.gov/askcfpb/search ...
http://www.consumer.ftc.gov/articles/pdf-0096-fair-credit-reporting-act.pdf
http://www.consumer.ftc.gov/articles/0149-debt-collection