Defence lawyer Shaun Russell asked for a discharge without conviction, saying a conviction would end Banks' 40-year career as a driver.
He said Naked Bus provided its drivers with a company cellphone and would text updates to the drivers if they needed to make specific changes to pick-ups or drop offs.
Mr Russell said drivers were to check before leaving, but quite often messages came in while they were on the road and the drivers checked them while driving.
``He accepts he was using the work phone but he never texts on them.''
Naked Bus chief executive Hamish Nuttall said Banks was employed by a third party contractor and no longer worked for the company.
He said all Naked Bus drivers were instructed that cellphones were not to be used under any circumstances while driving, in accordance with the law.
``Passenger safety is of utmost importance to us and we regularly remind drivers not to use their phone while driving other than with the supplied bluetooth headpiece.''
Mr Nuttall said the company used a custom-made automated booking system that enabled information to be sent directly to an app on a driver's phone.
``However, bookings are cut off before the bus leaves the previous compulsory stop. There is never any need for a driver to check any phone once behind the wheel.''
NZ Transport Agency (NZTA) spokesman Andy Knackstedt said police alerted the agency whenever a driver with a passenger endorsement, such as a bus or taxi driver, was convicted.
If the NZTA found a driver was no longer fit and proper to drive passengers, it could suspend their endorsement for up to 10 years or revoke it completely.
Mr Knackstedt said it was currently reviewing Banks' passenger endorsement.
Sentencing Banks this week, Judge Simon Maude said the summary of facts, to which Banks pleaded guilty, made it clear he was using a cellphone while driving and this was supported by the photograph taken by the passenger.
The matter was too serious to discharge Banks without conviction.
"The use of a cellphone while driving is rightly regarded by the public as a serious risk. The seriousness, in my view, is heightened when the driver is in charge of a large vehicle and, significantly, is a professional driver for members of the public.''