The other important regulation is that any form of trade of cell phone numbers is strictly forbidden. This means that you can not collect hundreds of cell phone numbers and then sell you list to as many telemarketers as you manage to. Cell phone numbers are not land line numbers and they can't be sold this way. There are of course exceptions to this rule, but you should bear in mind that selling or buying mobile phone numbers list is illegal in the US. For example if you enroll in some advertising list and allow the company to resale your private information, then they are allowed to trade your information. That is why you should always read how your data will be used by companies which demand you to give personal details such as name, address and phone number.
A few years ago there was an idea of creating a huge cellphone phone book. Thea idea come from two big telecoms companies which wanted to assemble their databases consisting of hundreds of millions of records. When the idea become public, there was a lot of buzz around this new project. Many people were complaining about privacy issues and stated that creating this kind of database is against the current US law. The arguments lasted for a few months and finally the telecomss gave up and the idea was abandoned. That was the biggest attempt to create a nationwide database with all US cellphone numbers.
Currently there are a few private owned companies which operate several data banks with cellular phone numbers. However, these are not often called cellphone books, the name reverse cell phone lookups is much more popular to describe this kind of business. Most of them operate abiding the US law and take care about people's privacy. They are not as big as the previously mentioned database were meant to be, but they still have around 40-60% of all mobile phone numbers operating in US. Access to them is usually based on a small fee.