The Signal Booster DUO (Band 12) is made of UNOBTANIUM

John

Your experience is very similar to mine.   Using Field Test on my phone *3001#12345#* I found that I had LTE coverage in my house is between -110 and -120 that changes between Band 2, 4 and 12 depending on the time of day.  4G coverage is usually pretty good.  The Cel-Fi usually locks to a strong Band 2 signal that is listed by the Cel-Fi app as T-mobile 3G CDMA and is always boosted.  Sometimes the booster will lock to a Band 4 LTE signal if that is the strongest one near the Window unit - otherwise it will stay lock to the 3G/4G signal and not boost LTE.  The Band 2 3G/4G signal is always boosted.

I sent the log into Cef-fi and started exchanging emails and yesterday spent over a hour with tech support (Evelin) on the phone (858-485-9442, Option 1). I discovered a few things.  She claimed that the strong Band 2 signal that was being boosted that is labeled as 3G CDMA could actually be a 4G T-Mobile signal.  Also - even though the new unit can boost Band 12, T-Mobile has decided to set the software to not boost B12 signals if there is any B2 or B4 signal available.  So even if B12 is the strongest signal received, the unit is set up to not boost it if a weak B2 or B4 signal is present.  However, the weak B2 or B4 signal may be too weak to be locked on by the booster and will not be boosted so the net result is that no LTE signal is boosted.  Evelin told me that Cel-Fi can send a signal to the Booster to allow the B12 LTE to be boosted but that should be the last resort if you are not getting any other band coverage,  I am fiddling on disabling LTE on my phone at home to get it to lock to 4G and see how that works first or to use Wi-Fi calling as a backup before asking for the software change.  I would suggest that you do the Field Test check to see what Bands are in your home and then give Evelin a call.  She is very patient and helpful.  Looks like you have a similar situation as I have.  Let me know how it works out.

Marty Melnick

Can you check my reply below...I finally believe I got the correct duo booster. I download the Cel Fi app and it shows the 700 mhz being found, but not boosting?

Marty,

I have had the same problem since December (my coverage inside the house will not pick up the signal except at a window). After many months I finally received the correct booster duo (after many returns). Your message helped alot and downloaded the app you suggested from Cel Fi, however the booster is not boosting the signal. The app from Cel Fi does show its finding the 700 Mhz frequency, but also a 1900 Mhz (believe it's At&t's signal). Although the app shows it's finding the signal, it said it was not boosting it? Not sure why not, so sent that to Cel Fi but haven't heard anything yet. If you have any suggetions or more I would appreciate. Glad hear you got fix on your end, hope can do the same here. I plug my unit up where I have almost 2 bars on my phone (iphone 7) and the signal on the phone works great at that window spot I have the booster set at. The window booster just flashes green, has been on all night. Thanks for any info.

John

Here's an update to my adventure.

After getting nowhere through this Forum, tech support or the Facebook Force, I sent off an Facebook email to the T-Mobile CEO and a TWEET to the Senior VP for tech Support.  Within a few hours I was contacted by the Executive Support group and the next day I was told that they had located two Band 12 Booster units for me (for my primary and vacation residences, both of which have poor coverage provided by Band 12.  Twenty-four hours later I had my two units.

Unfortunately, getting the units to boost my received LTE signal was tricky since (as I found out later) there is a strong 3G Verizon tower nearby that was capturing the booster unit.  T-Mobile provides minimal documentation with the unit so I couldn't get the Duo combo to boost the T-Mobile LTE signal.  My calls to tech support broght no joy.  As a last resort I went to the Cel-Fi website (they make the booster unit) and found out that they had an app that provides quantitative information of what the booster devices are seeing and how they are operating.  With this I was able to find an area that was somewhat shielded from the Verizon tower and gave me a 1-2 bar LTE signal (-110 dbm).  I have been able to get signals boosted to -80 to -90 in most of my house.  Tomorrow I will call into the Cel-Fi tech support to see if I can do better.

So my friends, I learned a few lessons.

1) The T-Mobile Executive team is very concerned with customer support and can get things done that the ordinary customer facing support team cannot do

2) The T-Mobile inventory system is chaos.  I kept on getting the old Duo unit being sent to me instead of the Duo+ (for Band 12) even though I explicitly asked for the Band 12 unit.  Even after I had returned two Booster units and two mini tower units using prepaid labels provided by T-Mobile, and signed off as having been received by T-mobile, I still get 1-2 letters a week threatening me with having to pay for the units if they weren't weren't returned by March 22.  It took 1 phone call for me to realize that the Level 1 CSR has no tools that will tell them the status of the returned gear.Even though I have an official letter that states that all of my boosters and towers have been returned, I still get a letter every Tuesdaty threatening me with a bill for $138 if the unit isn't returned by by March 22.

3) The Tech Support team (even the enhanced level support personnel are no help if you have a problem figuring out where to place the units.  They appear to be unaware of the WAVE software app from Cel-Fi that quantitatively shows the network environment and the operation of the booster units as you change locations.

On the positive side - I REALLY like my new iPhone 8 and the T-Mobile service.  In virtually everywhere I go in Orange County I get 3-4 bars of signal.  Unfortunately my house in Newport Beach is just in a low signal area.  About 1/4 mile away there are 3-4 bars of LTE.  There is a new tower scheduled to be installed nearby later in the year so coverage should improve.  Having unlimited calls and data removes second thought of picking up a Face Time call from my grand children when I am out of the house.  The Tuesday feeebies are neat and I picked up a subscription to MLB-TV and save $125.

I hope others can use this info to improve their service.  Unless you are in a barren area the combination of Signal Boosters and Wi-Fi calling should provide acceptable service.  If anybody needs some help navigating the Booster DUO+ arena, just drop me a message.

Marty

I've had mine since maybe FEB of this year. Works good. All my devices are working just fine, no drop calls, nada. It's all good.

reply from tmo_nicholas_t

<https://support.t-mobile.com/people/tmo_nicholas_t?et=watches.email.thread>

en Red y cobertura

"Hi Martin,

I'm sorry you were provided some misinformation. I just checked our

inventory levels and we have that model in stock right now."

HOW COULD YOU CHECK YOUR INVENTORY LEVELS AND FOUND THAT THE UNIT IS IN

STOCK? AMANDA SAID THAT YOU TOLD HERE THAT THE UNITS WERE PART OF THE SAME

INVENTORY. YOU CAN EXPLAIN TO YOUR CEO. I HAVE CONTACTED HIM AND SEND HIM

THE ABSURD RESPONSES THAT I HAVE RECEIVED ABOUT THESE BOOSTERS.

" Tech doesn't have the option of which option of booster to send.  

automatically defaults to whichever is in stock when your order is placed"

THIS IS THE STUPIDEST EXCUSE I HAVE HEARD IN THE TWO MONTHS THAT I HAVE

BEEN TRYING. FANFARE LAST NOVEMBER - WE HAVE A NEW UNIT THAT COVERS BAND

12. NOW I AM EXPECTED TO BELIEVE THAT THERE IS NO WAY TO SPECIFICALLY

ORDER SUCH A UNIT. NO COMPANY CAN BE THAT STUPID, ONLY PEOPLE WORKING AT

SUCH A COMPANY WOULD BE THAT STUPID, I HAVE EMAIL YOUR CEO LETTING HIM

KNOW ABOUT THE RUNAROUND I HAVE BEEN GOING THROUGH AND HAVE LET HIM KNOW

THAT YOU AND NIC HAVE GIVEN ME THIS ABSURD REASON.

¡Hola, @duhmel​!

I chatted with Nic a bit last week and he was able give me the info I passed along to you on Friday.  Tech doesn't have the option of which option of booster to send. It automatically defaults to whichever is in stock when your order is placed. It's a bummer to go through so many coverage devices attempting to get a specific model. Can you share your zip code with me? I'm not 100% sure that the band 12 coverage device will help out in your area but I'd love to check.

What is care and how do I contact.  When I call the regular number and get patched to tech support nobody knows what I am talking about