At last week's news:rewired conference, Garnett said that if he has learnt one thing from his years in broadcasting it is "don't carry lots of gear".
In a separate interview with Journalism.co.uk Garnett said that because he covers a huge patch he likes to carry as little as possible – but needs to be able to do the job properly.
In explaining how his iPhone is now his vital kit, he shared five examples of how he has used it in place of a video camera, satellite truck and radio car.
1. Icy moments
The night before news:rewired, Garnett "was camped outside a haulage depot in Bradford". He was using a portable satellite transmitter to broadcast and had it set up tested it in preparation for giving a live report.
A minute before the broadcast the the dish slid off the icy roof of his car.
So what did Garnett do? "I pulled out my iPhone, rang the newsdesk, told them to pick me up on a different outside source, closed the line down, opened an app called Luci Live, pressed connect and as they were reading the cue into me, linked into the studio and was able to broadcast as planned."
Garnett has been using Luci Live, an app that allows him to feed quality audio into a radio studio live, for iPad for about two years.
The £299 cost may rule it out as an option for many journalists but as a BBC solution he uses it regularly, the first time being the day that Ed Miliband came to the Labour leadership.
"I was sent to Doncaster to go and do a piece. It was a terrible day: it was windy, it was raining, and there was no way I could put a satellite up without it blowing off the roof of my car."
2. Audio from Amsterdam
Garnett explained that he recently went to Amsterdam to record a piece for BBC Radio 4’s You and Yours.
"I flew out in the morning, recorded the piece at lunchtime, had an hour to wait at the airport for my plane and by the time I landed at Manchester Airport I’d edited and mixed the piece.
"I was able to file the package to the producer as an email while I walked to the car."
Garnett advised journalists at the conference to "remember the photographer’s maxim: the best camera is the one you're carrying".
He said that an advantage of using your phone as a recording device means that not only do you always have it with you, you get it fixed immediately if it breaks. (Unlike Garnett's audio recorder which he confessed is sitting in a drawer after it broke a few months ago.)
3. A taste of Little Chef
Another example of a speedy turnaround is when Garnett was on his way to a story in Bristol when the news broke that Little Chef was shutting lots of its restaurants.
Garnet heard the news in a radio flash at 12.20pm. "I knew the next financial bulletin was at 12.50pm," he said.
"Ten minutes after the story was on air I drove past a Little Chef," he explained. "I pulled in and stopped three customers who were coming out. I edited and mixed the vox pops in my car and then I filed the audio as an email attachment."
4. A safer option in chaos
The riots last summer were dangerous for reporters, Garnett explained at news:rewired. In Manchester a radio car was burnt out.
"But using an iPhone held to my ear and connecting to a voice over internet protocol programme called Luci Live I was able to broadcast safely," he added.
"Using one device I was able to take stills, video, file copy, monitor TV, radio," he said.
5. Going live with video of floods
Garnett also told how he was reporting on flooding in Stockton-on-Tees in late summer.
"Sometimes even an organisation as big as the BBC doesn't have enough TV trucks," he said.
"I met a man who would have been great on the news channel but the nearest TV truck was 50 miles away."
Garnett then remembered that he had been sent an iPhone application called Dejero.
"It uses very clever technology to bind together a wifi connection with a 3G connection, so you can double the upload speed and bandwidth," he explained.
But despite having the app, there was still a challenge. "The problem was that it was raining, I didn't have a tripod with me, and I needed another phone to act as cue return into the guest's ear while they were on camera.
"I ran into the town centre, went to a pawnbrokers shop and bought a tripod for £5, a pay-as-you-go phone and got a beer tray to hang over the top of the iPhone and then set that up and put the guest onto the BBC News channel."
The process was also made possible by "some very cunning and clever trickery done by the guys at the studio end".I ran into the town centre, went to a pawnbrokers shop and bought a tripod for £5, a pay-as-you-go phone and got a beer tray to hang over the top of the iPhone and then set that up and put the guest onto the BBC News channelNick Garnett
"They had to borrow various bits of kit from other channels to make it work, but it was one of those real moments where the BBC is at its greatest; it just makes things happen and it makes things happen very, very quickly.
"Within 20 minutes of trying to get this up and running we managed to get it working and we managed to broadcast the guest."
Garnett told last week's conference: "This became the first broadcast-quality TV interview on the BBC using an iPhone."
And apart from a slight break up of the video with Garnett knocked the tripod at the beginning, the rest is good quality – "such good good quality that the assignment editor who is in charge of moving satellite trucks around, who knew that there wasn't a satellite truck in Stockton-on-Tees and couldn't get one there, phoned the news organiser at the BBC and asked 'whose satellite truck were you using there?'
"He couldn't believe that it was all being done on Nick Garnett's iPhone."
Garnett has not used Dejero since and says the technology should not be used for the sake of it.He couldn't believe that it was all being done on Nick Garnett's iPhoneNick Garnett
"It's always about journalism and whatever technical equipment you can use to make that happen. But it's always got to be first and foremost about the journalism, it's got to be about the story."
Garnett's tips: tools for mobile reporting
1. Use the internal iPhone microphone
Garnett says he uses the internal microphone rather than a mic and XLR cable as cables tend to break.
"It's more than sufficient for what I need and it means that in four years of use it's never broken down and never had to be repaired."
2. Don't use headphones with an inline mic
"Don't use the white Apple headphones that come with your iPhone if you are trying to monitor what you are doing because you will use the inline microphone on the headphones rather than the internal mic on the iPhone."
3. Get an app for multitrack editing
Garnett uses Voddio for editing audio. "I can edit three tracks of audio and get them playing at the same time," he explained.
He used to use 1st Video, which was also made by Vericorder. "The reason I like this company is it's made up of former journalists", Garnett said, explaining that they previously worked at Canadian broadcaster CBC.
Asked if he uses his iPhone when he has his computer handy, Garnett said: "I can't remember when I used a full sized laptop for editing".
"I used my iPhone for a nine-and-a-half minute package on 5 live the other week. That was nine-and-a-half minutes of solid audio and there were tracks flying all over the place, it was really quite a complicated piece to do.
"But the fact that I had the device with me, I didn't have to go and find my laptop, charge it all up, transfer the files from my audio recorder onto my laptop, probably convert them into a different sample rate. It's just simpler having the single one device.
For those who find the "finger fudging" difficult on the iPhone, an iPad - or an iPad Mini - might be a good way of working, Garnett suggested. The iPad app has 11 tracks of audio so can cope with extremely complex edits.
5. Use Voddio for video
Voddio also lets you edit a video package – "perfect for online newspaper journalists", Garnett said.
An iPhone and app (which is free but costs £6.99 to unlock sharing) gives reporters the ability "to film and edit and add tracks of interviews and overlay pictures in a new, imaginative way".
They can also "file that from their phone straight back to the studio in a very cost-effective manner as is crushes down the audio into a very small file form that means you are not going to be hanging around for half an hour as you try and squirt your audio or your video back to base", Garnett added.
5. Ensure connectivity
Whether using Luci Live or another programme that requires good bandwidth, Garnett says mobile journalists must ensure they have at least three bars on a 3G signal.
"The most important thing is that you have a good signal. If you don't have a good signal it will go wrong."
And by checking his signal before speaking to me, Garnett proved that a strong 3G connection was capable of streaming video. I interviewed him when he was at the Rivington Services on the M6 when he was on the way to Cumbria. He spoke to me via video Skype using his iPhone and a 3G connection and it streamed perfectly.
Mobile journalism has huge potential, Garnett said. iPhones are much lighter than the early reel-to-reel tape recorders, provide better quality audio than many handheld recorders, and are much cheaper than portable ISDN gadgets and satellite dishes.
Garnett explained that portable satellite dishes cost £5000 to buy and £5 a minute to run "even if all I want it to do is send it from Manchester City Centre to our studios in Salford".
"The advantages of mobile journalism are twofold," he said. "Firstly, we can broadcast from locations that were impossible before: hotels, hospitals, airports, office blocks." He has even broadcast from a tram as it went round Sheffield.
"Secondly, with a small amount of investment in technology and training we're able to have every reporter being broadcast capable whenever they're out and about – and that really is mobile journalism."
You can get more tips in mobile journalism by following Nick Garnett's blog.
Related: #Podcast – How iPhones to ‘green screen Nokias’ are being used for mobile journalism