You may be getting charged for unnecessary features like texting or calling off an iPad or data device. To avoid charges, block the feature.
If you are getting charged for texts or calls from devices other than a phone, you have the option to enable a block. Or, if you're noticing that your calls and texts aren't going through, you may want to check that the block is disabled. To do this, login to your Verizon account and search for your phone number. Scroll down and click on 'Manage Features'. Search for "Block" and turn the switch on/off for 'Block Messaging' and/or 'Block Voice Calls'. Press continue, scroll down, and then submit. After that, you're all set!