--- title: Messages Overview slug: electronic-prior-auth/guide/messages-overview docTags: createdAt: 2026-06-02T15:55:08.816Z --- The Messages Overview section describes the electronic message transactions supported by the Electronic Prior Authorization (ePA) Companion Guide and outlines their role within the prior authorization workflow. It provides a high-level summary of each message type, including its purpose, trigger events, and general processing expectations, to help implementers understand how requests, responses, and status updates are exchanged between trading partners. This section is intended to orient readers to the message ecosystem before reviewing detailed transaction specifications and implementation requirements in subsequent sections. Refer to the following topics for more details: ::::LinkArray{contentSource="DOCS" sourceParentDocId="GzbnuLVufR00sogKAR6HP" childrenDocs="[{"docId":"H3bGvZUDpr92PKlGTJB9z","docTitle":"Message Descriptions"},{"docId":"yXuvlLipJCkwIeIkcv1mk","docTitle":"Acknowledgment Messages"},{"docId":"H5ei5SmPD3JSHeqDbPqIb","docTitle":"Electronic Prior Authorization Message Flow"},{"docId":"q_WARI3KwstzO6VzzJAQS","docTitle":"Detailed Electronic Prior Authorization Message Scenarios"},{"docId":"CnwLR5R-eEwZpsE1nf3-l","docTitle":"PANotification Message Scenarios"},{"docId":"vj5tIYfJiQ9eSZVjZeoer","docTitle":"Validating PAInitiationRequest Data"},{"docId":"0KpD1sUh0QhxnL_9t10Gg","docTitle":"PAIntiationRequests After Real-Time Prescription Benefit (Real-Time Benefits Inquiry)"},{"docId":"Amvr_c2hDcv6IvfNhzZog","docTitle":"Directories"},{"docId":"IYNVwHfvYvFnzkZBh6c1S","docTitle":"Failure Mode/Response Approach"}]" itemsPerRow="1"} :::LinkArrayItem{headerType="NONE" docId="H3bGvZUDpr92PKlGTJB9z"} [Message Descriptions](docId\:H3bGvZUDpr92PKlGTJB9z) ::: :::LinkArrayItem{headerType="NONE" docId="yXuvlLipJCkwIeIkcv1mk"} [Acknowledgment Messages](docId\:yXuvlLipJCkwIeIkcv1mk) ::: :::LinkArrayItem{headerType="NONE" docId="H5ei5SmPD3JSHeqDbPqIb"} [Electronic Prior Authorization Message Flow](docId\:H5ei5SmPD3JSHeqDbPqIb) ::: :::LinkArrayItem{headerType="NONE" docId="q_WARI3KwstzO6VzzJAQS"} [Detailed Electronic Prior Authorization Message Scenarios](docId\:q_WARI3KwstzO6VzzJAQS) ::: :::LinkArrayItem{headerType="NONE" docId="CnwLR5R-eEwZpsE1nf3-l"} [PANotification Message Scenarios](docId\:CnwLR5R-eEwZpsE1nf3-l) ::: :::LinkArrayItem{headerType="NONE" docId="vj5tIYfJiQ9eSZVjZeoer"} [Validating PAInitiationRequest Data](docId\:vj5tIYfJiQ9eSZVjZeoer) ::: :::LinkArrayItem{headerType="NONE" docId="0KpD1sUh0QhxnL_9t10Gg"} [PAIntiationRequests After Real-Time Prescription Benefit (Real-Time Benefits Inquiry)](docId:0KpD1sUh0QhxnL_9t10Gg) ::: :::LinkArrayItem{headerType="NONE" docId="Amvr_c2hDcv6IvfNhzZog"} [Directories](docId\:Amvr_c2hDcv6IvfNhzZog) ::: :::LinkArrayItem{headerType="NONE" docId="IYNVwHfvYvFnzkZBh6c1S"} [Failure Mode/Response Approach](docId\:IYNVwHfvYvFnzkZBh6c1S) ::: ::::