It's very hard to track someone's signal from his mobile phone. The carrier might have an idea where you're calling from through the 3 tower triangulation, but they are not allowed to use it except in rare situations when it's a matter of danger. A usual person need very expensive hardware to actually capture the signal from your phone. Besides that, you can't hide the information from your SIM provider, because if you do so with custom tools and application, he will most likely block your connection to his network. There are some things you can't modify or tamper with.
