Prosecutors say the alleged hacking targets included supermodel Kate Moss, actress Joanna Lumley, royal family member Lord Frederick Windsor and Jamie Lowther-Pinkerton, then private secretary to Prince William and Prince Harry.
Edis said the guilty pleas show "there was a conspiracy which involved a significant number of people and it was quite a substantial conspiracy."
The hacking trial — which is not expected to end until Easter 2014 — is the first major criminal proceeding spawned by the revelation that the News of the World had hacked the mobile phone voicemails of kidnapped 13-year-old Milly Dowler, who was later found murdered.
Brooks, 45, edited the News of the World from 2000 to 2003 — Dowler's phone was hacked in 2002 — and went on to edit its sister paper, The Sun, and become chief executive of Murdoch's British newspaper division.
Coulson, 45, edited the News of the World between 2003 and 2007 before becoming communications chief to Cameron until 2011.
Brooks and Coulson face charges of conspiring to intercept communications — phone hacking — and conspiring to commit misconduct in a public office, which refers to illegal payments to officials.
Edis said the allegations include an accusation that Coulson while at the News of the World conspired with royal editor Clive Goodman to pay a royal police officer for a notebook containing contact details of members of the royal household.
