1) Most of the US carriers don't have options for "0 voice service, unlimited data service" on your phone (T-mobile does, but only with smartphones).

2) Most of the US carriers I've seen make unlimited data for your phone more expensive ($75-$110/mo. total, even with a dirt cheap voice plan). And that may or may not cover a tethering option. In comparison, the mobile router products, like Cradepoint's offering (and a couple other vendors), use data cards or USB dongles, which tend to get a reasonable flat rate unlimited service from the carriers ($40-$60/mo. total). Oh, and, at least with T-mobile, that unlimited internet tier covers using VOIP, so you don't need to ALSO carry a phone if you don't want to: just use Skype on your NIT (if you find Skype's quality to be good enough).

3) It uses Wifi for the bridge between your NIT and the network. This means you don't have worry about buying a phone that has Bluetooth DUN or PAN, and even if it does have DUN, wondering if it will actually work with the NIT. It also means that you can have more than one such device (a camera with that wifi SD card, for example).

4) Some bluetooth phones make you hit "OK" or something on every bluetooth connection, even if the devices were already paired and trusted the last time you connected them. This means you have to physically handle the gateway device every time you use it. With the PHS, you only have to touch it if it's not actually turned on. If it's in the bottom of your backpack, but on and just waiting for you, then you don't have to touch it at all.


That's how it's different from (and IMO, superior to) just carrying around your phone to tether with your NIT.