In, Out or Somewhere In Between
http://www.iabc.com/cwb/archive/2008/0108/Eschbach.htm

Eschbach, Peter A.
Communication World Bulletin
2008

Abstract:

When considering possible staffing models for structuring your corporate communication function, your choices typically range from the extremes of establishing an all in-house staff to totally outsourcing the function by enlisting the services of a PR agency (or agencies) to do it all for you. More common is the combination that takes advantage of the benefits of the two previous options, while hopefully minimizing their disadvantages.