Hi, if your phone is dropping calls occasionally, it is most likely a signal issue. However, frequently dropped calls may be caused by a damaged or incorrectly inserted SIM card. Other times, the phone may have physical or liquid damage. If your phone is frequently dropping calls, please try this step to see if they resolve the issue.
Verify that the SIM card is installed correctly and is not damaged. You can contact your carrier for assistance with testing the SIM. Alternatively, if you have another phone that works with the same carrier, try inserting the SIM card into that phone and test it to see if it still drops calls. If it does, you may need to get a replacement SIM card from your carrier.