No monthly fees, no need to connect to wifi.Works for all phones & cellular devices.Consistent service: faster internet, uploads, and downloads.Reliable reception: no more dropped calls, repeating conversation, or static-sounding voices.Better coverage: no need to be at a particular spot or do yoga poses to get signal.But not both.Everything changes with an T-Mobile Signal Booster. So take your pick: Better actual 4G LTE coverage, or prioritized Wi-Fi Calling traffic. One final note: T-Mobile tells me it will work with customers to get them either the 4G LTE Booster or the Personal CellSpot, but not both. Just remember that you have to pay a $25 deposit (or pay for it outright if you're a prepaid customer). If you're already using Wi-Fi Calling and you've noticed that call quality is spotty - maybe people can't hear you right, or there's distortion when you speak - then the Personal CellSpot may smooth out your local networking issues enough to provide you with a better experience. If you don't control your home Wi-Fi network or you have no intention of upgrading to iOS 8 - or if you just don't want to use Wi-Fi Calling, for whatever reason, the 4G LTE Booster will be your best bet. And I can tell you from experience that it just works. If you have at least one bar of 4G coverage somewhere in your home and you're a T-Mobile postpaid customer (in other words, you're on their Simple Choice plan or another plan that doesn't require you to pre-pay each month), you may be eligible to receive one of these devices. It doesn't require you to make any changes to your network and provide you with a practical way to stay in touch even if you can't get a cell signal where you are. If you're upgrading to iOS 8, or if you're buying a new iPhone 6 or iPhone 6 Plus, it makes sense to give Wi-Fi Calling a try and see how you like it. Also, pre-paid customers can get one, but they'll pay $99 for the privilege. Unlike the 4G LTE Booster, the Personal CellSpot does cost money - it's a $25 deposit. The idea is that even if you're using your Wi-Fi network for other stuff - transferring files, streaming videos from Netflix, playing games or whatever, when you get a call, it's going to be crystal-clear, without any sort of distortion or low quality. Wi-Fi Calling works with any Wi-Fi router, but what's different about the CellSpot Booster is that it's been designed to prioritize voice traffic over "regular" network data. It's optimized for Wi-Fi Calling, specifically. Unlike the 4G LTE Booster, the Personal CellSpot doesn't do anything to improve your actual cell coverage. Personal CellSpotĪnnounced recently at T-Mobile's "Uncarrier 7.0" event, the Personal CellSpot is T-Mobile's latest effort to improve coverage in your house. I went from lots of dropped calls in my house or "Call Failed" messages to four bars of coverage almost all the time. T-Mobile's offered a couple of different kinds of these boosters I've had one of these for a few months, and it works fantastically well. You don't have to connect the 4G LTE Booster to your Wi-Fi network (unlike with T-Mobile's Personal CellSpot or AT&T's similar device, the MicroCell), and there's no web interface needed to set it up or allow calls.