When I took the Sonic 4G to San Francisco, I used the mobile hotspot primarily with my tablet and smartphone. That was the mission of the trip, to see if I could make it without a laptop. My friend's WiFi and this device made that venture very successful for me. But did the love continue even after my mad experiment was over, and I was using the Sonic with all my machines and devices? Check it out, to see how it fared.

T-Mobile Sonic 4G Pros

Attractive rounded design, microSD slot that supports up to 32GB, USB tethering, battery life

T-Mobile Sonic 4G Cons

Inconsistent speeds, downloading large files can take a while or even choke a bit

Best For: Budget-conscious users with light to medium data needs
Company Website: T-Mobile
Price: $99 (with discounts and two-year contract); $175 full retail


At 4 x 2.2 x 0.6 inches and 3.9 ounces, the Sonic 4G is a small, lightweight device like other hotspot gadgets in its class. The rounded corners and smooth black finish on the front and sides give it (dare I say) a stone-like look and hand feel. The rear plate — made of soft-touch plastic — is removable for changing out the battery.

The Sonic also offers a microSD card slot (up to 32GB), which is supremely handy for wireless file sharing. But one thing I never understood is why manufacturers feel the need to block it with the battery, under the rear back panel. I can hardly deduct points for this, considering how many makers do it, but bear in mind that it does make it a pain in the neck to access. Aside from that pesky issue, file sharing was easy and worked well. (See below.)

Other details:
• Power button on the right, under the WPS button
• Bottom-situated microUSB port • Front OLED screen displays indicators for signal, battery, and number of connected devices

Size comparison with Palm Pixi


Once you turn on the Sonic 4G, signing on is a no-brainer. With a laptop or mobile device, all you have to do is find the network SSID and log in with the supplied password, and you're good to go. Other users — up to five total — can also log on simultaneously, with one being able to tether via USB.

File sharing is also user-friendly. First, enable file sharing by typing in "http://mobile.hotspot" in the browser of a connected device, put in the admin password, and hit the microSD tab to access web sharing settings. After that, it's smooth sailing. Of course, it's not as fast as having a card locally connected, but uploading or downloading data was easy and fairly fast for most modest-sized files.

Other details:
• Sonic users are able to send/receive texts via a web interface
• Goes in and out of standby mode quickly • Can be woken with data requests, bypassing the need for the user to hit any hardware buttons


It's impossible to review a device like this without also commenting about the network it's on. Now, T-Mobile claims that it offers America's largest 4G network, but I'll let others debate whether its HSPA+ 42 is actually 4G or not. All that matters to most end users is that it works, that it offers decent coverage and that it's fast.

To the first point: Yes, it works, and pretty well too. If you have T-Mobile coverage in your area, you will have a signal — whether that's via "4G" (where available) or its 3G network. Carrier maps will be important here, though. You'll have neither service if you're in a Tmo black hole. Speaking of coverage, Magenta has 191 markets covered, with 150+ enjoying HSPA+ 42 goodness. While that's certainly not everywhere, it does include many major metros and then some.

As for speed, well that was kind of a wonky thing. As I said, I used the Sonic in San Francisco, but I also traversed two more cities — New York City, as well as my hometown, about an hour north of Boston — and it seemed fairly fast overall. Predictably, T-Mobile sanctioned test areas gave me stellar speeds, while connection was slower in other areas. It was also a bit inconsistent. There were times my connection would reach way up (once, even to an incredible 16.37 Mbps down), then drop below 3 Mbps, and then jump back up. Was it physical interference? Network congestion? Other? Who knows? In the end, Speedtest.net gave the Sonic 4G an overall average of 9.12 Mbps (down) and 1.37 Mbps (up), at least in my usage.

But again — and I cannot stress this enough — coverage is key. At different times and places, it was better than competitors like Sprint's Overdrive Pro and AT&T's Elevate, and at other times, it was worse. (At no time, however, did it beat Verizon's 4510L, which other reviews have even clocked at a whopping 24 Mbps at times.)

People planning to use their tablets with this hotspot may not notice the inconsistencies for the most part — and indeed, I didn't have any problems while using it with my iPad — but laptop users who expect higher or more consistent throughput might have to reign in their expectations a bit. While regular web surfing performed reasonably well, downloading bigger files occasionally revealed some sputter and lag.

Battery Life

In a word, awesome. It's unusual when a device delivers its rated hours of battery life, but it's even rarer when it blows right past that. Official specs list 4.5 hours of continuous use (150 hours standby), but I often got 5 to 6 hours — sometimes even more. A lot depends on usage of course, so if you tend to download a lot of torrents or stream constantly, your mileage may differ. But for light to medium use — say email, web surfing, RSS feeds and the like — the battery life should be plenty.

Best part? Unlike many other portables, this router actually hangs on to a charge. I kept my hotspot in standby, and it lasted for several days with barely any difference in bars.

Data Plans and Value

Tmo is renowned for offering data plans with no overage fees, though it throttles users once they hit their limits. This approach holds true for the Sonic 4G as well.

The hotspot is currently selling for $99, with mail-in rebate, instant discount and two-year contract. This discount price comes with a choice of three Classic data plans: 2GB ($40/month), 5GB ($50/month) or 10GB ($80/month).

The carrier also offers a set of Value plans, though subscribers would have to pay the full $175 for the device to be eligible for them: 2GB ($29.99 /month), 5GB ($39.99/month) and 10GB ($69.99/month)


The design of the Sonic 4G makes it a delight to carry and use. I found that the mobile hotspot delivered well with my tablet and smartphone, as I don't tend to download large files or do hugely data-intensive tasks there. However on the laptop, where I usually do more of the "heavy lifting," the inconsistencies did become more noticeable.

If you have the funds and prize consistency/speed, I'd recommend the Verizon 4510L MiFi instead. At half the price of the T-Mobile offering, it costs less (upfront, anyway) and uses Big Red's fast LTE network. Penny pinchers, however, may prefer the Sonic. While not as fast as the 4510L, it's a good-functioning hotspot that will never incur overage fees. Add the fact that it offers file sharing, text messages and excellent battery life, and it's a very decent option.

See at Amazon

This post may contain affiliate links. See our disclosure policy for more details.