Colorado bans all cell phone use by drivers below 18—an officer may cite a driver for using a cell phone without any other traffic offense taking place. No exception for hands-free or voice-operated technologies, but the ban doesn’t apply to calls made to contact a public safety entity or during an emergency.
Colorado bans text messaging and browsing the internet for all drivers—an officer may cite a driver for texting or browsing the internet without any other traffic offense taking place.
"Using a cellphone while driving increases crash risk. Researchers have consistently linked texting or otherwise manipulating a cellphone to increased risk. Some studies, but not all, have found that talking on a cellphone also increases crash risk." -IIHS
The Insurance Institute for Highway Safety (IIHS)