London (CNN) -- Several hundred attempts were made to hack the cellphones of aides to princes Charles, William and Harry, the trial of two of Rupert Murdoch's former senior executives has heard.
A News International "private wire" -- which routed desk-based landlines through a mobile phone number -- was used 296 times by News International private investigator Glenn Mulcaire in an attempt to access phone messages of Mark Dyer, the heir to the UK throne's private secretary, Detective Constable Richard Fitzgerald told the Old Bailey court on Thursday.
And between October 2005 and August 2006 there were 416 attempts to hack the voicemail of Jamie Lowther-Pinkerton, private secretary to princes William and Harry.
The claims were made in the trial of former News Of The World editors Rebekah Brooks and Andy Coulson, who are accused of conspiring between October 2000 and August 2006 "to intercept communications in the course of their transmission, without lawful authority." They deny the charges.
Other former employees of the tabloid, which closed down in 2011, Stuart Kuttner, Greg Miskiw, Ian Edmondson, Neville Thurlbeck and James Weatherup, are accused with them. Thurlbeck, Weatherup and Miskiw have pleaded guilty.
Mulcaire was convicted of phone hacking in 2006, and has already pleaded guilty to hacking charges in the current case.
Earlier jurors were shown whiteboards taken from Mulcaire's office and home that featured telephone numbers, mobile phone networks' passwords and names, such as tennis player Venus Williams and Rebekah Wade, Brooks' maiden name.
The boards contained messages to avoid certain members of staff who worked for mobile phone networks. At the start of the trial jurors were played a tape of Mulcaire obtaining PIN numbers from mobile phone providers by pretending to be someone else such as an engineer, a practice known as "blagging."
Giving evidence in the trial, Fitzgerald said voicemail messages could be intercepted easily in the early part of last decade. Asked by the prosecution if this was due to a security failure of mobile phone network providers, Fitzgerald said: "I'd agree they were clearly not sufficient."
Earlier in the day Fitzgerald gave jurors an insight into how to hack a mobile phone.
The first way was to dial the cellphone number of the target; if it was engaged or turned off then the phone would go to voicemail. You could interrupt a greeting, Fitzgerald said, by pressing the *, # or 9 keys and listen to messages by entering a default PIN code, such as 3333 or 1010 depending on which UK phone network the hacking target was on as many users rarely changed these. If the hacker called the same number with two phones, the first call would make the line "engaged" putting the second call straight to voicemail. The first phone could even be set to terminate the call before the target was aware that they had been called.
An alternative was to dial a number that directly accessed a person's voicemail, Fitzgerald said. The hacker could then access messages by entering a code; again these were often not changed from the cellphone's original default setting.
As well as being accused of conspiring to intercept communications, Brooks, Coulson, Kuttner, Miskiw, Thurlbeck and Mulcaire face an additional charge of intercepting the voice mail messages of British schoolgirl Milly Dowler, who went missing and was later found murdered in 2002.
Brooks, her husband, Charlie Brooks, and her former personal assistant Cheryl Carter also face a separate set of charges of conspiring to obstruct the police investigation into phone hacking.
They were charged in May 2012, along with Brooks' former driver, a security guard and members of security staff from News International -- the then parent company of News of the World -- with attempting to pervert the course of justice.
The hacking scandal prompted British Prime Minister David Cameron to set up an independent inquiry, led by Lord Justice Leveson, to make recommendations on journalistic ethics and examine the relationship of the press with the public, police and politicians.
The trial resumes on Wednesday.