Yes, you can be charged. This depends on the service. For example, Spectrum’s Voice Residential Services Price Guide charges $3.95 for voicemail.
Website: https://www.virtualpbx.com/blog/general-telephony/professional-voicemail-greetings/

For a medical office, call types may include billing, emergencies, appointments, cancellations, etc. 2. Determine How To Best Route Calls The best method of routing your medical office calls will depend on your office size and budget. If you have a small staff, setting up a standard voicemail greeting system may be a more practical approach. For a larger health organization with multiple departments, it makes more sense to route calls to their intended destinations by using an auto attendant. For example, “If you have a question about billing, press 1. If you’d like to schedule an appointment, press 2. If this is a medical emergency, press 0 for an operator.” If you want every caller or patient to experience a professional and compassionate call, you may consider working with a medical office answering service. You can forward calls to an answering service after business hours, on holidays, during overflow, or any other time you may need help answering calls. 3. Draft A Script
In certain situations, it’s a good idea to let a call go to voicemail. If you’re in a loud area, unable to spend 10-15 minutes talking, or are otherwise distracted, don’t answer. Recruiters who cold-call candidates will understand that you’re simply unavailable – but make sure to return calls in a timely manner. If possible, call back during regular business hours.