I had the same issue with service in my apartment in the downtown of a major metro area with tmobile, some rooms I couldn't even talk or text... ever. lots of dropped calls too.

Tmo had Bad coverage in smaller towns too. Often times no 4g data, sometimes no data at all, and issues with talk and text reception (usually at most class c and d airports I had at least talk and text, and usually 3g data, but a lot of the nontowered airports I'd take the beechjet into had little to no service). I've switched to ATT, and haven't personally noticed any coverage issues... possibly because tmo coverage was so bad that ATT seems good.

Also beware of tmobiles 'no contract' plans. About 10 months ago my bill went from $105 for two lines to $130. They claimed they changed their price structure and no longer gave corporate discounts. I was told I could switch to a lower priced plans but would lose my hot spot. About 2-3 months later a $15 charge appeared on my bill for use of a hotspot (bringing my bill to $145/month for 1000 minutes, unlimited text, and 2gb high speed data on only ONE line). I went into a tmo store to get rid of this new charge, and supposedly they did away with mobile hotspots... if I switched to a 'new' plan with unlimited minutes I would save a little money but lose the hotspot capability completely. So I immediately went over to ATT and now have unlimited talk/text 15gb shared data with hotspots for two lines for $115/month after taxes fees and a corporate discount. The real kicker: tmo will bill you for the remainder of your current month PLUS an additional two months... I refused to pay additional 2 months of charges, and they took me to collections where I was forced to pay to save my credit score. Leaving tmo cost almost $500 altogether and I was NOT on a contract, and my phones were unlocked phones bought on amazon at retail price, not through tmo... I might as well have had to pay an early termination fee and had subsidized phones to keep.

Apparently there's a way to get a hotspot (or at least tethering) because a few people on here say they have it... I don't know if It was something not offered on plans in my area or if it was just $hitty customer service, either way I was told that the hotspot was only available on 'legacy' plans with a $15 fee.