Weak mobile signal is a fact of life here in Stroud, especially if you are in any of the valleys. One of our regulars in the co-working office has a work phone on Vodafone and it is particularly hard to get a signal on that network in the office. O2 works well enough and EE is OK in the right part of the office, but Vodafone is a non-starter.
So we invested in a Vodafone Sure Signal box which creates a femtocell in the office - to the layperson this means your phone shows "5 bars" - and routes the actual mobile traffic over the office internet connection.
Long story short, Vodafone are a customer service nightmare and it took many weeks to register the Sure Signal on their site, but by obtaining a new free Vodafone SIM and not putting any credit on it, today we finally managed to register using the new number provided with the SIM.
The upshot is we now have perfect Vodafone reception in the office, and having done some bandwidth monitoring while making calls, it appears to use almost no bandwidth (circa 12Kbytes/second) so having more of these boosters for other networks in future should be no problem at all given our shiny new 70Mbit/s fibre broadband.