Please go try troubleshooting your handset first. Then, try putting the sim to another phone and check out. If the problem was still on the connection within the other phone. You may contact globe for them to create a report on their end.
You may notice that they are doing nothing but don't worry. When they recieve about 3 or more reports in your area that were not under your name. They will do a cellsite inspection. However, if they detect no problem was found after several months. Seems to be your hardware or phone have incorrect settings.