(really need to add a chin rub smiley)
Tangent moment! (And a serious question from a layman for the experts.) What is the legal difference here between voluntarily providing certain information to a utility provider in order to acquire their services and providing certain information to a doctor or lawyer for theirs'? Both the former and latter are considered voluntary actions, and you can go without either, but the latter are strongly protected by confidentiality laws. Why are these other things (utilities) that are considered voluntary but necessary parts of daily living treated so differently with regard to privacy and thus, in this case, considered exempt from 4th amendment protections?
Lawyer thing is covered by attorney-client privilege. It is limited in scope, mind you. It only covers legal guidance, see Rule 501 of the Federal Rules of Evidence for more information. Doctor thing is covered under HIPAA.
As for why they are treated separately than any other type of information... There are three arguments. Doctor and lawyer confidentiality is considered long standing tradition, and oddly that is considered an important aspect by SCOTUS. Second is that people want their talk with doctors and lawyers to be confidential. And third, doctors and lawyers make enough money to prevent themselves from the government most of the time to some extent. There is no cell phone users' lobby to protect themselves from government malicious intent.
Get enough people with enough money and you could probably get cell phone use enshrined as protected.
Another interesting aspect I'd like to point out. Kinda unrelated to anything anyone has yet said.
Utilities are granted monopolies by the government due to the opinion that they are NOT voluntary and are entirely necessary for modern living. You could argue a cell phone is unnecessary and voluntary, and you'd be somewhat correct. But not in a legal sense. Telecommunication carrier is considered under the law to be a utility because it is considered to be one of the natural monopolies. A natural monopoly is when the infrastructure required to produce and deliver an 'essential' product is very expensive to build and maintain, and can add capacity at a fraction of the cost of what it would take to form a new company. Examples would be electricity, natural gas, water, telecommunications, sewage, etc. You could double, say, a water company's capacities for a fraction of the cost of a new company creating that capacity.
Telecommunication utility law usually does not differentiate between say, a cell phone, a landline or a DS-3 line. It's all considered to be telecommunication. Most of the differences in law are owing to basic physics. There's no law against jamming or wireless interception of DS-3 connections, for instance, because it doesn't use the airwaves. So if someone tries to argue with you that a cell phone is unnecessary, should be considered voluntary, and thus should not be accorded any legal protections (I question the logic of that assertion on its own grounds but anyways), remind them that historical public utility law entirely disagrees with him or her.
