Dont know about the US but in Australia its illegal everywhere! but only if you get caught :)

Legislative Bans- National Conference of State Legislature (NCSL) reports in 2002-2003 states in the US proposed over 100 bills concerning cell phones in automobiles.Five states considered an outright ban. New York was the first state to pass a law limiting cell phone use, a ban on hand held phone use. Afterwards, ten other states have passed laws regulating cell phone use while driving: AZ, CA, FA, IL, MA, MI, NJ, OK, OR and RI (and OH according to another poster on this question). Other states require police to include cell use in their reports of auto accidents: CA, FL, IO, MD, MA, MC, MN, MO, NB, NJ, OK, OR, PA, TN, TX and UT. As the number of accidents involving cell phones and other technologies continues to rise, legislators may feel more pressure to specifically restrict these technologies in cars, something the industry is trying to deter from happening. Much of the legislation currently in the books do not specifically regulate cellular phone use in automobiles. http://www.duke.edu/~gfb2/soc%20142%20webpage/Policies.html.htm

I live in Ohio its illegal her. If i remember right, it has been in affect almost a year know

All states in Australia.

I just called our local police station and asked if it was against the law to talk on a cell phone while driving in Ohio and they said as of right now no it is not against the law. The state may be working on a law to stop the use of cell phones while driving but no law like that is in effect now. May 27, 2008

May 11, 2009 Fox News article: Here is a list of the current laws that each state has on the books concerning text messages and cell phone calls while driving. Alabama: No Laws Alaska: Illegal for all drivers with the enforcement being primary, meaning that a police officer can pull over a driver for sending a text message even if he isn’t breaking any other traffic laws. Arizona: Only bans school bus drivers from speaking on their cell phone Arkansas: Illegal for all drivers with primary enforcement California: Illegal for all drivers with primary enforcement Colorado: No Laws Connecticut: Illegal for all drivers with primary enforcement Delaware: Illegal for novice drivers with a GDL to send texts or make phone calls with primary enforcement. Also illegal for school bus drivers to make phone calls. D.C.: Illegal for all drivers with primary enforcement Florida: No Laws Georgia: Only bans school bus drivers from speaking on their cell phone Hawaii: No Laws Idaho: No Laws Illinois: Only bans school bus drivers and those under 19 from speaking on their cell phone Indiana: Only bans those under 18 from talking or texting on a cell phone Iowa: No Laws Kansas: Only bans those with a learners license from talking or texting on a cell phone Kentucky: Only bans school bus drivers from speaking on their cell phone Louisiana: Illegal for all drivers with secondary enforcement, meaning a driver can only be pulled over for a different traffic violation and then ticketed for cell phone usage Maine: Only bans those under 18 from talking or texting on a cell phone Maryland: Only bans those under 18 from talking or texting on a cell phone Massachusetts: Only bans school bus drivers from speaking on their cell phone Michigan: No Laws Minnesota: Illegal for all drivers with primary enforcement Mississippi: Only illegal for those with a learner's license to text while driving Missouri: No Laws Montana: No Laws Nebraska: Illegal for all drivers with secondary enforcement Nevada: No Laws New Hampshire: No Laws New Jersey: Illegal for all drivers with primary enforcement New Mexico: No Laws New York: Only bans school bus drivers from speaking on their cell phone North Carolina: Only bans school bus drivers and those under 19 from speaking on their cell phone North Dakota: No Laws Ohio: No Laws Oklahoma: No Laws Oregon: Only illegal for those with a learner's license to text while driving Pennsylvania: No Laws Rhode Island: Only illegal for school bus drivers and those under 18 to talk on cell phones while driving South Carolina: No Laws South Dakota: No Laws Tennessee: Only illegal for school bus drivers and those under 18 to talk on cell phones while driving Texas: Only illegal for school bus drivers and those under 18 to talk or text on cell phones while driving Utah: Illegal for all drivers with secondary enforcement Vermont: No Laws Virginia: Illegal for all drivers with secondary enforcement Washington: Illegal for all drivers with secondary enforcement West Virginia: Only illegal for those with a learner's license to talk or text on cell phones while driving Wisconsin: No Laws Wyoming: No Laws