As you may guess or more likely even know already, TInet ain't the only system doing wireless services on a handheld device. On this page we want to sketch out a few alternatives along with their advantages/disadvantages over our system.
Some time ago TI started to develop an own system for wireless communication in the classroom. As Texas Instruments sells school tools, TI-Navigator seems to aim at supplying teachers with a system they can use for their lessons. For example all students get a certain task and the teacher can monitor their individual learning progress, show specific student's sollutions for a problem to the whole class and so on. I doubt TI allows students to get internet access during school... However as far as I know TI-Navigator hasn't finished beta stage, yet. Also I don't have access to specifications including system speed, supported calculators and so on. As far as calculators are concerned, a personal guess would be that only the newer calcs with Flash-ROM/Apps (TI-73, 83+, 89, 92+, Voyage 200) are supported.
Telnet8x + GrayLink + cell phone
If you grab Telnet8x off of ticalc.org, you will find a text document included, demonstrating the opportunity to connect to a Linux box over the "TI / RS232 adaptor" GrayLink and a cell phone. Of course this would also work with a normal line, but then it wouldn't be wireless. Also if you're at home anyway, it would be easier to just use your computer. Whilst an advantage of this solution is, that it can be used almost everywhere and - assuming the Linux box supports it - with a bunch of existing e-mail programs, ICQ, web browser Lynx and so on. Disadvantages include that first you got to have a Linux box accessible and above all that dialing in via cell phone will most likely be really expensive. Also Telnet hasn't been designed for devices with a 16x8 chars display which requires a somewhat uncomfortable user interface.
Telnet8x + GrayLink + Ricochet modem
Also shipped with Telnet8x is some information about Ricochet modems. These devices are standard modems on the PC (or in this case: calculator) side, yet they allow you to get an internet connection via radio. I don't know about prices, but most likely this is cheaper than cell phone calls (see above). The main problem of this solution seems to be that you need an access point (wireless internet service provider) nearby.
A more extensive coverage of this technique can be found on a dedicated Macross Software web page titled Wireless TI.
WAP is the first of the described systems which a lot of people/companies contribute to. It uses a cell phone for both retrieving and displaying information on the Internet. I never really tried WAP myself, but one may guess that it works rather good. Main disadvantages seem to be high cost, low bandwidth (GSM's slow 9.6 kbit/s) and lack of really useful information accessible (as you cannot use WAP to just browse the web as usual, but have to find specifically designed WAP/WML pages). After quite some marketing it turned out that WAP just wasn't as good as thought.
One may wonder if it's just marketing again, but if you believe the hype, UMTS is the big thing coming. Featuring a higher bandwidth compared to GSM and devices with more capabilities like higher resolution color displays, UMTS is at least very interesting. But again this sounds like UMTS is going to be expensive...