If you are having issues with an old microcell installation
I bought a microcell for my apartment, but I had problems because my at&t tower reception was too good and the handoff between microcell and towers is not very good. The calls would get garbled and drop. So I put the microcell in my girlfriend's house because she had horrible at&t reception. Before the microcell, calls would only go through about half the time, and they ususally dropped. After the microcell, things went well.
Fast forward to the present, and at the same time at&t's merger with T-mobile was killed my and my girlfriend's phones start getting garbled calls and calls dropping in her house. I recognised that it was the same type of problem I had at my apartment. Just to test a hypothesis, I unplugged the microcell, and suddenly she had decent reception from the local towers. There is a new roaming agreement with T-mobile that was implemented after the failed merge. Apparently, she now has a good signal due to a T-mobile tower.
Not saying this is going to always be the case, but it may work if your microcell has recently started having problems.