My interest in digital radio modes has recently grown, which has led me to the world of messaging with DMR. I will be discussing the various ways of sending a message using DMR and APRS. While the concept is similar for all DMR radios, I may make specific reference to the Anytone 868 which is my personal favourite DMR radio. This guide is for people with a DMR hotspot (as I cannot speak on how to do this using a DMR public repeater). When I refer to a “DMR Channel”, I mean a channel with the frequency of your hotspot, and a valid talk group selected.

DMR Direct Messaging

You can send a direct message between two DMR radios. You must know the other person’s unique DMR id (You can lookup ID by callsign at THIS WEBSITE). Start by selecting a DMR channel on your radio. On the Anytone 868, the function will not work if you do not have “Single Slot” or “Double Slot” digital monitor on, and it will not work unless you have selected a DMR channel in either your primary or secondary channel on the radio. 

In order to send the message, go to the menu tab and click messages. Select “Create new message”. To send a message via DMR, simply type your message into the “compose message” box. Once you are done, select the send message button, select “Manual Dial”, and type the DMR id of the other amateur you are trying to contact. You can save time by adding them as a contact to the radio if you message them often. You may receive a notification saying “Message successful” or “message not sent”. I have noticed this message to be inaccurate, and I have received a “message failed” warning despite the message sending successfully.

PLEASE NOTE: Both radios MUST be on the same talk group in order to receive DMR direct messaging. This means that you must have keyed up your radio so your hotspot starts listening to the talk group. 

APRS Messaging

If you are not on the same talk group as someone, but you would still like to send them a message, you can do this via APRS messaging.  

To start, go to the messaging tab, then select “create new message”. Now, you need to type the other station’s APRS callsign into the compose message box. My Anytone 868 radio identifies itself as “M7OJA-5” when sending APRS messages. You can visit one of the many only APRS websites in order to search up the other station’s callsign. I am unsure whether this system works if both operators are not registered on the Brandmeister selfcare system. if you are not, you should create an account and setup digital APRS broadcasting for your radio.

Once you have typed the other station’s callsign and your message, you are ready to go. A composed message should look like:
“M7OJA-5 Test message 123” (Remember that the callsign in the message should be the RECEIVING station’s callsign – NOT your own. You do not need to include your callsign in the message, as this is sent automatically with your APRS message.

Then click send, and click “manual dial”. You now need to dial the talk group of your Brandmeister host server’s APRS system. Don’t worry if you don’t know what this means. Brandmeister has many different servers. My DMR hotspot is registered on the Irish server as this is faster than the UK server. You can search on the Brandmeister wiki for the relevant country that your hotspot is registered on.

If, like me, you have your hotspot registered on the Irish server, you can use talk group 272999 to send the message. After you have selected “manual dial”, type 272999, and click send. The message will then be sent to the DMR server, uploaded to the APRS network, and then the message will be forwarded as a normal DMR message to the recipient.

You can find which talk group to dial on the Brandmeister wiki under the relevant page for your hotspot. For example, if your hotspot is registered to the UK server, you can use talk group 5075 to send your APRS message.

You should receive an SMS confirming that your message has been sent successfully via APRS. Please don’t send any sensitive information via APRS, as your message is published on tens of sites across the internet.

To respond to a message you receive via APRS, do NOT use the “reply” or “respond” feature of your radio. You should go into messages, compose a new message ensuring that the APRS id is correct.

PLEASE NOTE: Some stations have multiple APRS callsigns. For example, if you sent a message to M7OJA, it would send it to my laptop, M7OJA-5 would send it to my phone and laptop, and M7OJA-B would send it directly to my hotspot and wouldn’t be received. Make sure you select the correct callsign for the RADIO of the receiving user. Remember, you can lookup an active APRS callsign using an APRS website (I tend to use https://aprs.fi/)

If you struggle to send a message using the radio, you can download the APRSDROID app for Android (And pay a small fee for the privilege). This lets you send and receive APRS messages from your phone. There are many similar free programs for Windows, including APRSIS32 which sends APRS messages over the internet, for free, and allows you to scan and receive incoming messages.

APRS Email

You can send an email using APRS. Repeat the steps in the paragraphs above, but instead of composing your message as:
“M7OJA-5 Hello”, for example, compose your messages as following:
“EMAIL oscar@m7oja.com HELLO”
Start with the word EMAIL. This directs your message to the email server. Next, include a valid email address. After that, state your message. Send this message to 272999 (or whichever talk group your Brandmeister Host Server uses for GPS/APRS), and the email will be sent.

APRS SMS

You can send an SMS text message for free using APRS. Repeat the steps in the paragraphs above, but instead of composing your message as:
“M7OJA-5 Hello”, for example, compose your message as following:
“SMSGTE +44123456789 HELLO”
Start with the word SMSGTE. This directs your message to the SMSGTE service. Next, include a valid phone number with the country prefix at the start. Do not structure it as 0044, for example, you MUST use the + symbol. This can be found by pressing the 1 button repeatedly when in Capital Letter writing mode on your Anytone 868. Send this message to 272999 (or whichever talk group your Brandmeister Host Server uses for GPS/APRS), and the message will be sent.

Legality of APRS SMS/Email Service

In the United States, it is legal under the “Third Party Traffic Rule” to send a message to be forwarded to a non-amateur. However, in the UK, the law is not so clear. You are not permitted to pass a message to a non-amateur under your licence conditions, however, the SMSGTE and EMAIL system is operated by a licenced amateur.  The law remains unclear on the topic. I have contacted OFCOM and the RSGB for clarification on this, and I await the result. In the meantime, please only send emails and sms messages via APRS to licenced amateurs.

Please share this article on Facebook or on your own website if you have found it useful – It is my aim to help out newer M7 operators, and hopefully this article will find its way to those who could benefit from it.
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Have fun!

73 de Oscar M7OJA