T-Mobile has done a lot to improve its network in recent years, but there are still places where you can't get a good signal. The carrier has long offered devices to boost signal, and it quietly snuck out some new versions of them this month. T-Mobile is now offering the CellSpot V2 and Signal Booster Duo to qualifying customers for (mostly) free.

If you have some signal in your home, but coverage is lacking, you can grab the Signal Booster Duo from Tmo. This device is placed where you have the best signal (at least one bar) and acts as a repeater to connect up to 16 voice and 4 data sessions in a 3,000 square foot area. It operates on bands 2, 4, and 12. None of its past signal boosters have supported band 12. If you have poor signal, T-Mobile will let you borrow this device free after a $25 deposit. If you cancel service, you'll need to send it back.

For those with no T-Mobile signal at home, there's the new CellSpot V2 (above). This device plugs into your router and sets up a tiny cell tower on the T-Mobile network. It supports up to 16 users (8 on LTE and 8 on 3G) on bands 2 and 4. The old version only worked on band 4, and it was bulkier. This device covers about 3,000 square feet, but you can't block any devices from connecting. That means other T-Mobile users could connect and use your internet data via the CellSpot. Just something to remember. This device is also a loan, so you have to return it if you cancel service.