Dave - what you are referring to is the TEXTING law...specifically VC23123.5
OP was not charged with violating VC23123.5
Zigner, read my response again and go to the DMV website. I will repeat the relevant portion for you. I will also point out that the the DMV site I referenced actually discusses VC23123 in its discussion.
Text Messaging Law Effective January 1 2009 Cellular Phone Laws Effective July 1 2008
(New Motor Vehicle Laws for 2009 )
Wireless Communications Device and Wireless Telephone Laws FAQs
Cellular Phone Laws Video — View Video with Open Captions | View Video
The new Wireless Communications Device Law (effective January 1, 2009) makes it an infraction to write, send, or read text-based communication on an electronic wireless communications device, such as a cell phone, while driving a motor vehicle.
Two additional laws dealing with the use of wireless telephones while driving went into effect July 1, 2008.
The first law prohibits all drivers from using a handheld wireless telephone while operating a motor vehicle, (California Vehicle Code [VC] §23123). Motorists 18 and over may use a “hands-free device. The second law effective July 1, 2008, prohibits drivers under the age of 18 from using a wireless telephone or hands-free device while operating a motor vehicle (VC §23124).
Below is a list of Frequently Asked Questions concerning
these laws. (note that it is plural, not singular)
Q: When did the wireless communications device (no texting) law take effect?
A: The law took effect January 1, 2009.
Q: When did the handheld wireless telephone laws take effect?
A: The laws took effect July 1, 2008.
Q: What is the difference between these laws?
A: The first law prohibits all drivers from using a handheld wireless telephone while operating a motor vehicle, (California Vehicle Code [VC] §23123). Motorists 18 and over may use a “hands-free device.” The second law prohibits all drivers from texting while operating a motor vehicle (VC §23123.5). The third law prohibits drivers under the age of 18 from using a wireless telephone or hands-free device while operating a motor vehicle (VC §23124).
Q: What if I need to use my telephone during an emergency and I do not have a “hands-free” device?
A: The law allows a driver to use a wireless telephone to make emergency calls to a law enforcement agency, a medical provider, the fire department, or other emergency services agency.
Q: What is the fine if I’m convicted?
A: The base fine for the FIRST offense is $20 and $50 for subsequent convictions. With penalty assessments, the fine can be more than triple the base fine amount.
Q: Will I receive a point on my driver license if I’m convicted for a violation of the wireless telephone or wireless communication device law?
A: No. The violation is a reportable offense; however, a violation point will not be assigned to your DMV record.
Q: Will the conviction appear on my driving record?
A: Yes, but the violation point will not be added.
Q: Is there a grace period, or will motorists get a warning?
A: No. The laws became effective July 1, 2008, and January 1, 2009. Whether a citation is issued is always at the discretion of the officer based upon his or her determination of the most appropriate action for the situation.
Q: Are passengers affected by these laws?
A: No. These laws only apply to the person driving a motor vehicle.
Q: Do these laws apply to out-of-state drivers whose home states do not have such laws?
A: Yes.
Q: Can I be pulled over by a law enforcement officer for using my handheld wireless telephone?
A: Yes. A law enforcement officer can pull you over just for this infraction.
Q: Can I be pulled over by a law enforcement officer for using my wireless communication device?
A: Yes. A law enforcement officer can pull you over just for this infraction.
Q: What if my phone has a push-to-talk feature, can I use that?
A: No. However, the law does provide an exception for those operating a commercial motor truck or truck tractor (excluding pickups), implements of husbandry, farm vehicle or tow truck, to use a two-way radio operated by a “push-to-talk” feature. A push-to-talk feature attached to a hands-free ear piece or other hands-free device is acceptable.
Q: What other exceptions are there?
A: Operators of an authorized emergency vehicle during the course of employment are exempt, as are those motorists operating a vehicle on private property.
Q: Are there exceptions for dialing?
A: This law does not prohibit reading, selecting or entering a phone number, or name in an electronic wireless device for the purpose of making or receiving a phone call. Drivers are strongly urged not to enter a phone number while driving. 
