Edmondson is the eighth journalist from the now-defunct Rupert Murdoch-owned tabloid to be convicted over illegal activities.
He initially went on trial last year alongside colleagues including former editors Rebekah Brooks and Andy Coulson, but was dropped as a defendant after a judge declared him unfit to stand trial.
He pleaded guilty last month to conspiring to intercept voicemails between 2000 and 2006.
Passing sentence today, Judge John Saunders said Edmondson had suffered from depression and other medical problems and had lost his job and his reputation as a journalist.