After purchasing Droid RAZR M you might be a little dissatisfied, since the phone has a signal problem, based on users reviews the device has difficulty to get 4G signal and frequently dropped to 3G. When compared to other Android phones like the Droid RAZR Maxx in the same location, this phone often gets a 3G signal even 1x while the Maxx locked to 4G.
In addition to dropping 4G problems, there are some users who experience other issues such as the “Your call cannot be completed” issue, when try to call a number it says connected but the target phone never rings, and problem of dropping calls problem.
When we take a look at the signal strength (you can see it in Settings > About > Network) Maxx getting around -75 dbm (3 to 4 bars) while M get -96 dbm (1 to 2 bars), so it can be seen that the signal strength difference is quite striking, about 20 dbm but it depends on the 4G coverage in your area.
These problems need to be resolved since it will also affect the battery life, the phone will need more power to find the best signals. Maybe someday Motorola will provide a radios update for Droid RAZR M, so dropped calls or 4G problems can be sorted out.