re "strange to choose 3g": as some operators even phase out 3G completely, we can expect 3G base stations to be available cheaper than ever. That's only one of the reasons: Osmocom started out from the security analysis perspective; having 3G openly available is a benefit to the general public as well as small business in various ways.
(The opening lines of https://osmocom.org/news/30: "3G is dead, you may think. From the perspective of large scale operators, that may well be the case, but this is precisely the reason why Open Source support for 3G is becoming increasingly interesting: when the focus for earning money shifts towards LTE infrastructure, the threshold for setting up 3G networks is becoming easier to surpass for everyone else.")
(The opening lines of https://osmocom.org/news/30: "3G is dead, you may think. From the perspective of large scale operators, that may well be the case, but this is precisely the reason why Open Source support for 3G is becoming increasingly interesting: when the focus for earning money shifts towards LTE infrastructure, the threshold for setting up 3G networks is becoming easier to surpass for everyone else.")