Will a signal booster work for both phone calls and data (internet)?
There are two types of amplifiers that come in a cell phone signal booster: five band and dual band.
Five Band Signal Boosters
Five band signal boosters will boost voice calls, 3G, 4G HSPA+ and 4G LTE data, so you'll have better voice calls and faster data for any network that you're on. These boosters will also boost Voice over LTE, so if you're making voice calls over the 4G LTE data network (something that most new phones do) then you'll have better calls there as well.
Dual Band Signal Boosters
Dual band signal boosters will boost voice calls and 3G data, so you'll have improved phone calls and faster 3G data speeds, but 4G LTE and Voice over LTE calls will not be boosted or improved.