The texts revealed Faapoi had been working with three people - an inmate, his partner and an associate - to organise the delivery of the contraband.
Faapoi was paid more than $1000 on several occasions for his services.
The messages were in code.
The contraband was referred to as laundry or clothes and Faapoi's payment was called a "church donation".
Faapoi was also asked to deliver cannabis to the prison but refused.
He denied taking in anything other than the tobacco but Justice Geoffrey Venning said all evidence pointed to that being the case.
Crown prosecutor Bruce Northwood said the offending was serious because of the breach of trust to the public.
He said in his role as a prison officer he put the interests of the public "in jeopardy" by harming the integrity of the prison system.
"He was prepared to take things to prisoners - that should never have happened," he said.
"In the interests of deterrence and denouncement, a term of imprisonment must follow."
Defence lawyer John Mather said Faapoi was a "relatively inexperienced" prison officer and was not used to handling inmates.
He said Faapoi had no previous convictions and aside from this offending, was of good character.
"He accepts what he did was wrong," Mather said.
"He also accepts and expresses remorse."
Faapoi was supported in court by his family.
Family members and other people including his current employer had supplied the court with letters of support, outlining Faapoi's good character.
He is no longer working for Serco.
Justice Venning said while Faapoi denied taking in the cellphone or cards, it made little difference to the gravity of the offending.
"You deny it… but I do not consider the difference will affect the sentencing," he said.
"I am required to hold you to account for the harm you have done to the community by your offending."
He said the offending was not only dishonest - as a prison officer, Faapoi breached the trust of the public and his employer.
"You did so for your own personal gain," Justice Venning said, sternly.
"I need to promote in you a sense of responsibility for the harm you've caused.
"You will be well aware of the seriousness of your situation and offending… the potential difficulty your offending has caused other prison officers.
"Introducing contraband into prison makes life more difficult for honest prison officers."
Justice Venning said Faapoi's co-offenders had all been sentenced.
The serving inmate was sentenced to nine months in prison to be served alongside his current sentence and the other two were sentenced to 10 and 11 months' home detention respectively.
Justice Venning said he had to be consistent with Faapoi - but also reflect that he was in a position of power and trust when he offended.
"You said that the offending began when you were a relatively new employee and under pressure from various prisoners," Justice Venning said.
"The prisoners employed relatively sophisticated methods to induce you… threatened you from an early stage.
"There is no excuse - you should have reported the matter to your superiors rather than letting yourself be swept up by the prisoners.
"I accept, however, that you are not a sophisticated person and the prisoners realised your naivety and to a degree, took advantage of that.
"Despite that, you took money for your actions, you knew what you were doing."
Justice Venning said Faapoi had no previous convictions which was a mitigating factor.
The fact Faapoi had refused to take illicit drugs into the prison was also in his favour when it came to sentencing.
He said a pre-sentence report stated the 37-year-old had a good insight into his offending and was "truly remorseful".
Faapoi had also written a letter to the court saying he understood how he had let down his employer, his colleagues, his family - and the community.
He gave Faapoi a discount for his lack of criminal history, for his early guilty plea and his remorse, meaning the possible prison sentence was two years.
That meant Faapoi was eligible for home detention.
"I take into account your personal qualities and the pre-sentence report which confirms you have a low likelihood of future reoffending," said Justice Venning.
"For those reasons and on balance, I accept that you are suitable for home detention and that is that appropriate sentence in your case."
He sentenced Faapoi to 12 months home detention.
Serco spokeswoman Jane Palmer said as soon as Faapoi was found with contraband he was suspended from duty.
"And following our internal investigation, dismissed with immediate effect," she said.
"Tobacco, like a number of other items, is contraband in New Zealand prisons.
"All prisons must deal with the challenge of contraband and regrettably, the potential for staff corruption, both of which can significantly disrupt and compromise safety and good order.
"We expect high standards of integrity from our staff, the vast majority of whom are hardworking and honest.
"We have zero tolerance for any actions that compromise safety in prisons or the wider community."
