In direct messaging vs fax in healthcare, Direct secure messaging can replace fax between providers who both have a Direct address: it is encrypted, can confirm delivery and can carry a structured summary of care. It falls short when the other party has no Direct address, cannot be found in a directory, or sends scanned pages that still need reading.
What Direct secure messaging is
Direct secure messaging is a standard for sending health information to a known recipient, built on the same transport as email. Each participant has a Direct address issued by a health information service provider (HISP), the company or network that runs the Direct service. Messages travel between HISPs, which handle the encryption and trust checks.
The ONC Interoperability Standards Platform page on unsolicited push of clinical health information to a known destination says the Direct Standard is based on the Simple Mail Transfer Protocol (SMTP) and was approved as an American National Standard. Its formal name is the Applicability Statement for Secure Health Transport. The same page notes that Direct interoperability may depend on establishing "trust" between two parties, which is why HISPs join trust communities.
A Direct address looks like an email address, but it only works with other Direct addresses. The CMS FAQ on updating digital contact information says the main purpose of a Direct address is for providers to exchange health information with each other, and that it is not meant to serve as regular email for the public. The same FAQ lists where addresses come from: EHR vendors, state, regional and local health information exchanges, and private HISPs.
Security is built into the message itself. The ONC certification test method for 170.315(h)(1) Direct Project checks that the payload is encrypted with the receiving site's public key and signed with the sender's private key.
What a Direct message carries
A Direct message has a body and attachments, like email. The attachment that matters most is usually a summary of care document in the Consolidated Clinical Document Architecture (C-CDA) format, which is structured data a receiving EHR can import. The CMS measure specification for Support Electronic Referral Loops by Sending Health Information asks the referring clinician to send a C-CDA that the receiver can incorporate electronically. Messages can also carry PDFs, images and scanned pages. The ISP page lists an XDR and XDM for Direct Messaging specification for packaging documents with metadata.
Direct messaging vs fax for sending one referral
Direct messaging and fax can both deliver the same referral, but they produce different results on arrival. A fax delivers page images that staff must read and key. A Direct message can deliver a structured summary the receiving EHR imports, plus a delivery notice to the sender. The worked example below follows one fictional referral both ways.
The example uses invented details throughout. A primary care office refers a fictional patient, Rosa Delgado, date of birth 03/14/1961 (example), to a cardiology practice for evaluation of palpitations. The referral includes an order, the last visit note, a recent lab panel and an ECG report.
The fax route
- The referring medical assistant prints the order and attaches the visit note, lab report and ECG report, or exports them to a PDF.
- She looks up the cardiology fax number on an old referral list and sends 11 pages.
- The fax machine prints a transmission report saying 11 pages went through. It proves the call connected, not that anyone at cardiology saw the pages.
- At cardiology, the pages land in a shared fax inbox with 140 other faxes received that day (example count).
- An intake coordinator finds the referral, matches Ms. Delgado to an existing chart or creates a new one, and keys the name, date of birth, insurance, diagnosis and reason into the scheduling system.
- The lab values and medication list stay as images attached to the chart until a clinician reads them.
The Direct route
- The referring office creates the referral in its EHR, which builds a C-CDA summary of care from the chart.
- The office looks up the cardiology practice's Direct address in its directory and sends the message with the order attached.
- The office's system requests a delivery notification, and the receiving HISP sends one back when the message is delivered.
- At cardiology, the message arrives in the EHR's Direct inbox. The C-CDA can be imported, so problems, medications and allergies appear as data for reconciliation.
- The intake coordinator still confirms insurance and books the visit.
The comparison
| Measure | Direct messaging | Fax |
|---|---|---|
| Delivery proof | Delivery notification from the receiving HISP when requested | Transmission report showing the call connected |
| Structure | C-CDA summary can be imported as data | Page images only |
| Directory lookup | Needs the recipient's Direct address from a directory | Needs a fax number, which most partners publish |
| Partner reach | Only partners with a Direct address and a trusted HISP | Almost any office, payer or facility |
| Security | Encrypted and signed per message | Depends on the line, the machine and where pages land |
| Work on arrival | Reconcile, confirm insurance, schedule | Read, match, key, then schedule |
The ONC test method page says a certified HISP must produce delivery notifications if requested, which is the basis for the delivery proof row. Steps 1 to 3 on the fax route also have a weak point the Direct route avoids: an outdated fax number sends PHI to the wrong place with no warning.
Why haven't Direct addresses replaced the clinic fax number?
Direct addresses have not replaced the clinic fax number because finding the right address is hard, not every partner has one, and staff habits and workflows are built around fax. Direct only works when both sides participate and the sender can look up the receiver. A fax number is printed on every letterhead.
Directory gaps are the biggest barrier. The ONC data brief on interoperability and methods of exchange among hospitals in 2021 reports that 70% of hospitals said it was difficult to find providers' Direct addresses. In the same brief, 69% of hospitals often or sometimes sent summary of care records by mail or fax, and 68% sent them through HISPs that enable Direct messaging. Both channels run side by side.
CMS has tried to close the directory gap. Its digital contact information FAQ says the 2020 Interoperability and Patient Access final rule led CMS to publicly report the names and NPIs of providers without digital contact information in the national provider directory, NPPES. A listing does not guarantee that anyone at the practice checks the Direct inbox.
Partner adoption is uneven. Many of the parties a clinic exchanges paper with, such as payers, home health agencies, durable medical equipment suppliers and some smaller practices, may have no Direct address in use. Fax reaches all of them with one number.
Attachment habits also keep fax alive. Staff are used to bundling a stack of pages and sending it. When they move to Direct, they often attach the same scanned stack as a PDF, which keeps the paper workflow inside an electronic wrapper. The broader reasons fax survives are covered in the post on the interoperability gaps that keep the healthcare fax machine running.
Do Direct messages still need processing on arrival?
Direct messages still need processing on arrival when they carry PDFs or scanned pages instead of a structured C-CDA. A C-CDA can be imported as data, but a PDF of a faxed lab report is still a picture. Someone must read it, match it to the patient and key or confirm the values, just as with fax.
A Direct inbox can fill with three kinds of content:
- Structured summaries. A C-CDA summary of care. Problems, medications and allergies can be reconciled into the chart without retyping.
- Born-digital PDFs. A visit note or report printed to PDF by the sender's system. The text is selectable but has no field structure.
- Scanned pages. Paper that was scanned and attached. These behave exactly like a fax image and need OCR or a person to read them.
The second and third kinds are where intake effort goes. A cardiology practice that receives a Direct message with a scanned 18-page packet (example) has the same work as a fax: split the documents, identify the patient and pull out the fields scheduling needs. The steps for that are in the routine for referral fax processing, which applies to scanned Direct attachments too.
Some of those attachments are document types that Schema Care reads, such as lab reports, discharge summaries and medical records pages. It returns each field with a confidence score and a link to its spot on the page, and you can try the threshold on a fictional sample in the interactive demo.
For teams building their own intake on top of Direct, parsing C-CDA attachments and handling message metadata are integration topics, gathered in the developer integration category.
Hand-offs where fax beats Direct messaging
Fax beats Direct messaging when the other party has no working Direct address, when the receiver is a payer or a non-clinical business, and when an urgent order must reach a machine someone watches. In those cases, sending by Direct risks a message that nobody opens or that cannot be delivered at all.
Partners without a HISP
If a lookup turns up no Direct address, or the address belongs to a HISP outside your trust community, the message may fail or bounce. Fax is the fallback that works. Keep a record of which partners accept Direct so staff do not guess each time.
Payers and non-clinical recipients
The CMS FAQ describes Direct as a channel for providers to exchange health information with each other. Payer forms, prior authorization requests and replies often travel by other routes, such as fax or a payer portal. Check each payer's published submission options rather than assuming Direct will reach them.
Urgent orders
A delivery notification confirms the message reached the receiving system. It does not confirm a person read it. For a same-day order, a call plus a fax to a monitored line may still be the safer route until the receiving team watches its Direct inbox as closely as its fax tray.
Mistakes when switching
The common mistakes are switching without telling partners, leaving the Direct inbox unmonitored and attaching scanned stacks instead of a structured summary. Each one loses the advantage Direct offers. Run both channels for a period, track which referrals arrive each way, and move partners over one at a time.
Referrals have their own electronic options beyond Direct, such as portals and EHR referral modules. The trade-offs on completeness, tracking and staff time per referral are laid out in the comparison of fax vs electronic referrals.