Carriers have to pay feature licenses at switch such as caller id, call forward, etc.. But still thats nothing compared to what they are charging all customers.
said by Its a Secret :
As an ex mobile phone employee, I can tell you text, caller ID, call forwarding etc. cost providers nothing. The capability came as a direct result of digital network implementation.
Your're being ripped off to the N-th degree... it's pure gravy like the system and access fees.