I recently wrote a blog about how all of the cellular companies are now offering unlimited data plans. Today I’m going to look at their plans in some detail to discuss what they really mean by “unlimited.”

AT&T. AT&T now has two unlimited plans. Unlimited Choice starts at $60 for one phone with unlimited voice, text and data. It’s $55 for a second line and $20 each for lines up to ten. There is an extra fee of $5 per month for one line or $10 for multiple lines if the customer doesn’t elect autopay. Data comes with lots of limits. Video is capped at 480p standard resolution. Total download speed is limited to 3 Mbps with video capped at 1.5 Mbps, regardless of the quality of the 4G stream available. And while there is no data cap, AT&T starts throttling data speeds for the month when a customer hits 22 GB of download. And last – and what will be a killer for most potential customers – it doesn’t allow tethering.

The Unlimited Plus plan starts at $90 for the first phone. It also includes a penalty for not using autopay. It undoes all of the speed restriction of the choice plan and can stream HD video. It also allows up to 10 GB per month for tethering. It has the same monthly cap of 22 GB before the data gets throttled. This still is not an alternative for home use because of the 10 GB cap on tethering. But it’s a good business travel plan. And a home user with a tablet might find this to be a good, if expensive, broadband alternative.

Verizon. Verizon’s unlimited plan is $80 for the first phone, $60 for a second, $22 for a third and $18 for a fourth. This also has unlimited voice and text. The data has a very unusual daily cap and speeds get throttled after hitting 500 MB download in a day. There is also a monthly cap of 22 GB, after which all data gets throttled. There is a 10 GB monthly allowance for tethering, with speeds throttled to 3G after hitting that cap. Verizon allows HD video streaming.

T-Mobile. T-Mobile’s plan is priced at $70 for the first phone, $30 for a second, $41 for a third and $19 for a fourth. This also has unlimited voice and text. There is a monthly cap of 28 GB after which data gets throttled. There is a 10 GB monthly allowance for tethering, with speeds throttled to 3G after hitting that cap. T-Mobile allows HD video streaming.

Sprint. Sprint’s plan is priced at $50 for the first phone, $40 for a second. But these are promotion prices and the company warns they will probably price to ‘market’ after March 31. This also has unlimited voice and text. There is a monthly cap of 23 GB after which data gets throttled. There is a 10 GB monthly allowance for tethering, with speeds throttled to 2G (which has been discontinued in much of the country) after hitting that cap. Note that at 2G you can’t even read email, so this is effectively a hard cutoff.  Sprint allows HD video streaming capped at 1080p quality.

Various Issues. There are activation fees to consider with some of the companies. AT&T and Sprint charge $25 and Verizon $30. T-Mobile has no activation fee. T-Mobile also includes all taxes and fees in its price, something that can be fairly expensive in some parts of the country.

None of these plans is truly “unlimited” and I won’t be shocked to see the Federal Trade Commission going after all of these carriers for advertising them that way. Certainly none of these are going to be a good alternative for home broadband, except perhaps for rural customers with no better alternative. But I think even rural users will find the cap on tethering and the throttling after a fairly stingy amount of download to be impossible to live with. It’s a shame because many rural homes using traditional cellular broadband have monthly bills of $500 to $1,000.

Interestingly, I just saw yesterday that some Wall Street analysts are slamming Verizon because they fear that their network cannot handle these new ‘unlimited’ plans. But as you can see these plans are not unlimited. They are effectively capped at 2 – 3 times the size of existing family plans, that that assumes that customers will use all of the allotted data-  which many will not. There is already plenty of excess capacity to handle this at the vast majority of cell sites. And this isn’t going to much hurt the cell sites that are already over-busy.

For customers that routinely go over the current cellular data caps these might be a great alternative. Current cellular data is priced at $10 per gigabyte and these plans have reduced data prices to a more affordable price under $2 – $3 per gigabyte for somebody that uses the full allowance. But compared to traditional plans these plans all have hard monthly caps – and while those caps are at 22 GB or higher, they are effectively hard caps since data gets throttled and becomes largely unusable after hitting the cap. These plans will all tease you into watching a lot of video and then penalize you heavily for watching too much.