The U.S. Copyright Office determined that consumers cannot enjoy full legal use of their cell phones because of software locks added by the providers block access to the phones’ programs. Since ownership of the cell phone is technically that of the customer, restricting the software means that they are putting an artificial limit on the hardware.
For those of you choosing to stay with your provider, the advantages come with features that are locked out. For example, many providers lock out the feature allowing you to transfer ringtones or pictures taken with a camera phone to a computer using a data cable so that they can charge you for transfer over the network. Ringtones and such are big business.