Which of the following pieces of guarantor information is required when establishing a patient's financial record?

The requirement for a phone number when establishing a patient's financial record is based on its necessity for communication purposes related to billing and account management. Having a current phone number allows the healthcare provider to reach out to the guarantor regarding any financial matters, such as payment reminders or inquiries regarding the account. This form of direct communication is essential for effectively managing billing processes and ensuring the prompt handling of financial obligations.

The other types of information can provide useful insight or assist in various aspects of patient care and administration but are not universally required for establishing a financial record. For instance, a Social Security Number is important for identification and billing purposes, but it may not be mandatory in every situation. Prior medical history is relevant for treatment but does not directly pertain to financial records. Emergency contact information is essential for patient management but is primarily utilized for safety and communication during medical emergencies rather than for financial management.