SMS

Service Overview

RRI Operates a short-messaging gateway for Winlink users to send a one-way SMS text message to a cellular subscriber without an opt-in by the recipient, and without needing to know the recipient’s carrier. The service was developed to support their “I AM SAFE” program for emergency communications, namely health and welfare, and utilizes individual carrier’s email-to-SMS-gateways for the last mile delivery. For decades these commercial gateways have been available but were not reasonable to use for this type of messaging as the sender needed to know the recipient’s cellular provider gateway in order to know where to send the message to. The messages would then be sent in an email format as phone-number@carrier’s-server.com

The RRI SMS Gateway automates the lookup process which would otherwise need internet connectivity to reach services such as freecarrierlookup.com. Messages sent to the RRI server are automatically routed to the appropriate carrier’s gateway for delivery. The service can be represented by the following graphic:

Manual Relay

While the majority of these messages are automatically relayed, in June 2025 AT&T became the first major carrier to “sunset” their email-to-SMS service. To address this RRI introduced a relay service to bridge this gap. With this update messages will be manually relayed when the phone number: does not have a working carrier-email-to-sms-gateway, is a landlines and not a cell phones, and for when numbers can not be looked up. To the latter point, the underlying service has a %99 accuracy rate, but all of these situations the message is passed to a RRI traffic handler for manual lookup, or relay as a voice telephone call, or SMS message. To use this relay service the message must be sent with the Winlink form “RRI Quick Message Welfare” which is found under the Radiogram & RRI Forms in the Standard Forms.

A New Service

RRI is actively developing a replacement service to moves away from reliance on the carrier’s legacy email-to-SMS gateway and instead injects a Winlink message directly into the SMS network bypassing the carrier’s gateways. In this second version the major hurdle is regulatory. There are many existing services which can easily provide this service, but they require the recipient to opt-in to the service prior to a message being sent. This of course would never work for a program like “I AM SAFE.” We are actively looking for partners in the project at the organizational level as well as if you are a developer/programmer, have experience with SMS servers or service providers, or in regulatory matters. Please contact N1LJK for more information.

Frequently Asked Questions:

• HOW QUICK IS THE SERVICE ?
  Text messages are usually received in minutes, however sometimes it may take a few hours to deliver. This is due to throttling the speed of emails relayed in order to prevent the appearance that the service is sending SPAM, which would result in service failures.
  
• MY MESSAGE WAS NOT DELIVERED
  The RRI Server relays messages. It is not the sending service nor the final delivery service. Its important to do some troubleshooting before reaching out.
  • Was it manually relayed? This is processed similar to priority traffic, it is not instant.
  • Test the carrier Gateway. Lookup the destination number using freecarrierlookup.com which can indicate whether the number was a landline, no gateway, or otherwise will provide the SMS gateway to send a test email from a commercial email provider. If delivery fails this would indicate likelyhood that it is the carrier’s gateway.
  • Test your Winlink system by sending an email to your commercial email account to ensure your Winlink messages are being sent.
  • Logs. All incoming messages are logged at the server and we can lookup how the Gateway handled the message. Contact N1LJK.
    
• WILL THE SERVICE SUPPORT MMS?
  We don’t want a service that only works some of the time, do we?  In developing this service it was discovered that some MVNO’s (resellers) do not work with MMS, but do with SMS.   The inception for this project was to avoid needing to know a carrier to send a TXT, therefore providing a reliable and usable service. But yes, it could easily do MMS.
  
• CAN THE RECIPIENT REPLY TO THE MESSAGE ?
  The service was designed to be one-way and while technologically possible, bi-directional messaging is outside of the scope of this program.
  
• ARE THERE LIMITATIONS ?
  • Possibly Volume. The gateway has not been stress tested. That is flooded with messages in a short period of time, although there are exercises planned.
  • Length of message. There is 130 character limit to the gateway between the emaill subject and body. This is the minimum number of characters found with various carriers. The Winlink form is specific to health and welfare messaging and uses some of these characters for the subject, name, and date and that the message is one way. The remaining characters for the form’s use are 92 less the characters in the first name.
  • Winlink only. The server will only relay messages from licensed Winlink operators.
  • Manual Relay. Manual relay is only available when using the form for the “I AM SAFE” program. If not using the form, bad numbers are returned to sender rather than relayed.
  • US/CANADA recipients (carriers) only.
    
• CAN DELIVERY BE TRACKED ?
  No, only delivery to the carrier. All messages are logged.
  
• HOW TO CONTACT THE DEVELOPER ?
  N1LJK or via the website contact page, select “SMS GATEWAY ADMIN”
  
• HOW DOES THE SERVICE WORK ?
  A picture is worth a thousands words, but a flow chart is better.

Please do not abuse this service as it is intended for health and welfare messaging

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AMATEUR RADIO & WINLINK:

Sending A SMS text message via the Winlink Radio Messaging Service

EXAMPLE: Offline with no other resources such as cell service or grid power, an emergency responder and Amateur Radio Operator sends a basic message to a concerned loved one outside of the impacted zone.  The only known information is the cell phone number. 

What is Winlink?
Winlink (Winlink Global Radio Email) is a worldwide system for sending and receiving email via radio, particularly useful in areas where internet access is limited or unavailable. It leverages amateur radio and government frequencies to establish radio networks for messaging. Winlink is used by amateur radio operators, emergency services, and other organizations for communication, including email, position reporting, weather bulletins, and message relay.

What is Amateur Radio?
Amateur radio, also known as ham radio, is a popular hobby and service that allows individuals to communicate with each other using radio frequencies, often for recreational, educational, or emergency purposes. It involves licensed individuals experimenting with and communicating through radio technology, often without a commercial or pecuniary interest.

Putting it together, an example:

Example of the Winlink Software Package with a message to construct.

Instead of entering a message to another Winlink user, the sender uses a form to enter the data to be sent

The form then populates the message to be sent

The Message is then sent via Amateur Radio, here is a typical radio station in the field (image) linked from OH8STN

And the message being transmitted

The message is relayed

It is transmitted over Radio to a Receiving Server.  These can be several miles, or thousands of miles away.

The receiving server then sends the email to the RRI Gateway which parses the email to lookup the cell phone users provider and associated carrier.   It also looks up the carrier’s email-to-SMS gateway.

It then relays the email to the carrier’s service, or if that is not possible it sends it to a RRI Liaison Operator to manually relay as voice phone call or SMS.

The Carriers service ports the message as SMS into their network and onto the recipient’s phone.

Here is the final message as received as SMS text message

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Special Thanks to Marc at Data247.com for use of their API for the Amateur Radio Community.
Thank you to N2NOV for resources of their VPS.

Development by RRI, N1LJK