Have a similar problem in the house as well as the shop. My shop doubles as my office and warehouse, so missing calls is NOT AN OPTION! I had been running 2 microcells for ATT. Run off internet. Basically turn phone into VOIP. But now my phone all have wifi calling capacity. So I just use that. I have strong wifi in both locations. Besides the router/wifi for the shop, and if your phone has that capacity, should be the ticket without any specialized equipment.
