The best opinion I can find on this subject is
People v. Nelson (2011) 200 Cal.App.4th 1083 [132 Cal. Rptr. 3d 856]. While some posters in this thread may argue that the citation is inapposite, because the court dealt mainly with the defense's argument that the law shouldn't apply to drivers who have momentarily stopped, the case sets valuable precedent in other areas too.
First, they resolve the defense's contention, which isn't applicable here.
Next, the court consulted legislative history and determined that the primary purpose of VC 23123 is to address the Legislature's "
concerns about the public safety hazards caused by drivers' hand-held use of wireless telephones while on the public roadways..."
The court further found that even fleeting use of a wireless device in traffic:
[W]ould likely create hazards to themselves and public safety by their distracted use of their hands on their phones and devices, and would likely cause further traffic delays, whether it be because of a poor response to traffic issues that arise (including if they are hit by another vehicle), distracted drivers' feet letting up on brakes, the failure to promptly move as required by the traffic laws, the inability to resist the temptation to continue their fleeting use of their wireless telephone as they begin moving again, or innumerable other reasons.
Finally, the court found that VC 23123's language didn't require the court to construe the statute narrowly because the legislative history and common sense interpretation of the law made it clear that it's the distracted use of a hand-held wireless device that the legislature is trying to regulate. While your circumstances aren't identical to the driver in this case, they're close enough that it should be difficult to persuade a court that your use of your phone wasn't also a public safety concern. In
Nelson, the court was clear that the distraction caused by having your hand on your phone and your eyes off the road is part of the public safety concern that the Legislature was trying to address. You're given the legal right to file an appeal, but you'll have to convincingly rebut the argument posed by the court in
Nelson: that distracted use of a cellphone, even if you aren't using it to place a call, poses a public safety hazard.