T-Mobile is set to announce a new device that will purportedly offer “full-bar” coverage for your home, even in areas that offer little or no tower-based cellular signal. The “4G LTE Cellspot” plugs into your home’s router and uses your internet connection to provide the cellular connection you may be lacking.  To make this even more enticing, T-Mobile is offering this device free of charge ($25 deposit required) for all post-paid (as opposed to pre-paid) customers. Suspicious yet of this gift-horse? Good for you if you spotted the hitch.

Here comes the sucker punch:

The self-proclaimed “un-carrier” isn’t the first to offer this sort of device: ATT, Verizon and Sprint all have similar devices, with one glaring exception: you can’t limit who has access to the T-Mobile device plugged into your router and using your bandwidth. This might not be a problem for those blessed with larger homes or big yards, but the Cellspot is designed to boost signal for any T-Mobile device within 3000 square feet. The device works by routing cellular calls (and data) via your internet bandwidth, which may or may not be capped, depending on your provider. Translation: any T-Mobile device, yours or a complete stranger’s, will consume bandwidth on your dime. On top of this, any data bandwidth transmitted via this device still counts towards your bandwidth limit (if you have one), even though you aren’t technically using T-Mobile’s infrastructure to transmit that data. All of sudden, that device ain’t looking so “free” anymore, eh? All said, if you are among the unfortunate who suffer from poor cellular coverage in your home or office and rely heavily on your T-Mobile cellphone, and you have the fortune of having plentiful broadband coverage (with no bandwidth caps) this device might be the ticket to glorious full-bar coverage. Caveat emptor, and always beware carriers bearing “gifts”.