@ahkfilm check the settings of your calling and/or contacts app, do you have any contacts listed as blocked? These would not ring but go directly to voicemail.
Depending on your model of phone, check your settings to see if you have it set to receive only calls from those people listed on your contact list; therefore blocking unknown callers.
If android, try to check the settings under your calling app, under Block numbers. You may see something called "Block unknown/private numbers. If that is ON, turn it off.
If apple, try to turn off Silence Unknown Callers, go to Settings > Phone, then scroll down, tap Silence Unknown Callers, and turn off the feature.
