Ross and Brand both apologised for their behaviour
Jonathan Ross and Russell Brand's lewd calls to actor Andrew Sachs were a "deplorable intrusion with no editorial justification", the BBC Trust has said.
Chairman Sir Michael Lyons supported Ross's 12-week suspension, adding that no further action would be taken.
He said the furore could have been avoided if BBC management had followed the corporation's editorial guidelines.
Steps taken to ensure there is no repeat of the incident include creating a register of high-risk programmes.
It was "not rocket science" to have expected a show featuring Ross and Brand to cause trouble, Lyons said.
BBC Trust chairman Sir Michael Lyons on who was to blame
The trust, which acts as the BBC's watchdog, recommended tougher penalties for staff who do not comply with editorial guidelines, and that there should be tighter controls on shows made by companies owned by their performers. Brand's show was made by his own firm.
Referring to the incident, broadcast on Radio 2 on 18 October, BBC trustee Richard Tait said three main failures were made - in exercising editorial control; in following established compliance systems and a failure of judgment in taking editorial decisions.
'Catalogue of failures'
"It was a very offensive programme which should never have been recorded. Once the offensive phone call was made, the recording should have stopped and senior management alerted," he said.
"It is a catalogue of editorial and management failures," he added.
Mr Tait said the offence of the original broadcast was compounded by Russell Brand's appearance on Chris Moyles's Radio 1 show on 21 October, when the pair talked about the incident.
He said this discussion, in itself, was also in breach of editorial guidelines in respect of privacy, offence and the fact it was broadcast at a time when children were likely to be listening.
Mr Tait added that the trust considered Brand's "unacceptable, so-called apology" broadcast on Radio 2 on 25 October "exacerbated the intrusion into privacy and the offence".
However, he said the trust considered the BBC's response to the controversy to have been appropriate.
'Overtly sexual context'
Georgina Baillie: 'I wanted them to be sorry'
The trust also upheld complaints about an edition of BBC One's Friday Night With Jonathan Ross from May, in which which Ross swore in conversation with actress Gwyneth Paltrow and TV personality Michael Aspel.
Mr Tait said Ross had "used the f-word in an overtly sexual context", using coarse language to tell the actress he wanted to sleep with her.
But Mr Tait did not think the two issues were comparable, saying in the case of Ross's TV show there were "fine judgements" which had to be made.
The trust had overruled an initial decision by the BBC's own editorial complaints unit.
"We thought it absolutely was not on the right side of the line," he said.
He added: "The people who made the programme, who are usually very skilful at deciding where the line is, made a wrong judgement.
"You have to allow an organisation like the BBC to make a judgement call which turns out in hindsight to be not quite right."
The trust also censured the BBC for a Ross show featuring Gwyneth Paltrow
But Mr Tait added that using sexual language in the way Ross had was "gratuitous, offensive, and should not have happened".
"There is a debate that needs to be had about what editorial guidelines really mean," he said.
Asked if any further action would be taken against Jonathan Ross, Sir Michael said: "It is not the job of the trust to make decisions about the terms and conditions of performers or the sanctions that are applied to them."
"We are very clear that the director general has taken the right action with respect to Jonathan Ross."
Pressed further on the issue, he said it was a "fundamental constitutional position" that the trust could not direct the BBC to hire or fire its presenters.
"There is a slippery slope in responding to pressure. Where does it end? It starts with comedians, and it ends with making judgements about who presents the news," he said.
'Tired of all this stuff'
Brand quit his Radio 2 show after the incident and Radio 2 boss Lesley Douglas also left, along with one of her executives.
The trust also announced that, in light of the difficult economic circumstances, BBC executives would be forfeiting their bonuses in 2009.
The BBC said in a statement that it was "determined to act on the lessons learnt from this incident".
Ross and Brand left messages about Sach's granddaughter
"In particular we will consider carefully the BBC Trust's ruling on the use of language and audience expectations," it said.
The BBC's deputy director general Mark Byford added that the incident was not "an example of something that is endemic within the BBC".
"It was a very, very serious failure in a radio programme where editorial judgement was exercised that seriously let the BBC down," he continued.
Reacting to the BBC Trust report, Andrew Sachs' wife Melody said: "Andrew has got nothing to say. I don't suppose he wants to do anything more about it.
"We are so tired of all this stuff. Whatever they do, they do, but we are so tired of it all."
Mr Sachs' 23-year-old granddaughter, Georgina Baillie, who was the subject of the crude calls, said she was "happy" with the Trust's findings.
"It is now time to draw a line under the matter and move on," she added.
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