How so? It's all using data right?
Actually no, it is not all data.
How the internet interacts with a phone is different then a pc. For example, phones can signal to sites to send only the mobile version, custom compressed images, and limit certain interactions, for example you could never play an online pc video game with a phone.
Let us look at a specific example. Steam. Steam is not available for the phone, so the "data" to the phone is zero. Pc's can access steam and the gigabytes of data that it can deliver. One connection from a phone to steam would cost less then 2Mb. One connection from a tethered phone to steam could cost 20 gigabytes. Same goes for youtube, which degrades the video for mobile devices. Peer networks are the same.
A pc is meant to engage the interent on a whole differnet level, with the latest smart phones that level is slowing disappearing.
But regardless of all of that. Data is not just data.
When you place a phone call it takes frequency to make that call. If you add up all the calls, data, and text frequencies, you get between 15-25mhz of frequencies. Now we all know spectrum and frequencies are limited. Which means that you cant really talk all day long or download all day long, because your sprint simply does not have enough frequency for you to do that. It has enough for you to do it randomly for a period of time, but the system depends on you stopping, so some one else can start.
The connection to your phone, unlike pcs, is not made for 100% connected all the time, in fact it is made for you to be connected less then 1% of the time, which is not really possible with most pc's.
But ignoring that. Data is still not all equal.
As I pointed above, frequency is limited. Wimax/LTE use frequency to a level of efficiency that is amazing, but it is still limited. So it not much data you are sending, but what kind of data you are sending.
All data in limited systems needs to be broken in to cast system.
1.) Live voice and video streaming.
2.) Server stored voice and video streaming.
3.) Latency sensitive Apps. Facebook, twitter, and other "broadcast" system.
4.) Web pages and text pages.
5.) Email and other none time related data.
6.) Bandwidth hogs that are always 100% connected.
Why?
Because if a Live video is disrupted by network lag, it ruins the user experience. If your video/music is stop to load, mid video it is annoying. If you are latency sensitive apps are stalled, you can miss real time events, (instant message from you boss telling you that he needs a ride to work, like this morning.) After that point it really does not matter, email, webpages, ect all work on the fact you can reload them later.
On a 3g system, there is no way to know what is being sent where and how it is being sent. 4g systems can tell and do adjust, but 3g systems do not.
Since there is no way to tell with 3g and no way to shape traffic make sure the data that has to get through actually does, you have to limit interactions to those services.
When you pay for tethering, you are paying for access to an system that is every overloaded already! When you use that system, there is about an 80% you are disrupting someones experience.
Why? Because number 6 is the most used of all them, accounting for 80% of all traffic daily. With no way to control massive data hogging uses, peer-to-peer, for example. The system will become over ran very quickly.
So the take home.
1.) Cellphones are not pc's, you can download hundreds of gigabytes of files with most pc's, but with a phone you are usually limited to about 32 gigabytes.
2.) It takes frequency for you to connect with the internet, that is very limited.
3.) There is currently no real way to shape 3g traffic to make sure time sensitive data arrives consistently.
4.) Most tethered data directly disrupts the network traffic, in most cases. Charging a premium for that disruption allows the carrier to build a better network.
With both wimax and lte, these problems do go away. Wimax/lte can detect when a voice call or video is accessed and adjust the network for that. Data hogging programs that degraded the network, can be adjusted for. Spectrum efficiency is increased many fold. Moving voice to voip will almost double that spectrum.
But data is never, "just data".
