Sending text messages over ham radio with JS8Call

Winter Field Day is coming up in the ham radio world, which invites ham radio operators to take their gear outside and get some hands-on experience with emergency communications. We’ve talked about sending email with Winlink, but I’ll show you another trick that lets you send SMS text messages over JS8Call, which is a lot easier to use than Winlink.

We last discussed JS8Call when I participated in an AmRRON exercise to track the grocery supply chain. I went into deep detail on the setup and how it works in that post and won’t repeat everything, but here’s a quick rundown:

JS8Call is like a chat room that works over ham radio. Think IRC or Slack.It works over HF, which means you’ll probably want a General license to take advantage of it (but Technician-class operators have data privileges on 15 meters). It requires a real-time clock, either provided by an Internet time server or through GPS via a GPS USB dongle, which lets you operate off-grid.

JS8Call is one of the best digital modes to learn, as it’s relatively user friendly, let’s you automatically exchange status messages with other operators, and lets you relay messages so you can reach operators you couldn’t otherwise.


But JS8Call has another superpower: it can tap into the extensive APRS data network. APRS is short for Automatic Packet Reporting System, a radio data network that’s been around since the ‘80s.

Well before cell phones were popular, hams could use APRS to send text messages, get weather reports, and track object locations. These days, APRS is tied into the SMS network.

APRS works over short-ish range VHF/UHF, but thanks to the JS8Call integration, you can tap into it from anywhere in the world.

To send an SMS text message over APRS, send a message in this format:


The format must be exact. Note that there are three spaces between :SMSGTE and :@NUMBER, and yes, you must put the “@” before the phone number.

If you hear about this on YouTube or elsewhere, you may see a different, older format that has since changed. The one above is now the correct format as of January 2022.

Screenshot of how it looks:

JS8Call-SMSIt takes a few seconds for the message to send, and then around another 30 seconds until the recipient receives it.


One thing to know: when you do this you’re sending a cell phone number over public airwaves. Also, it will be logged in the APRS system for all to see. Finally, the recipient has no way to respond to your message.

However, if you have a power or telecommunications outage, JS8Call gives ham radio operators a simple way to contact loved ones even if they aren’t hams themselves.


  • Comments (18)

    • 5

      This is awesome info to share.  I am so inspired to get my HAM license – a 2022 goal. 

    • 6

      Thank you, Josh. This is excellent information. It makes me wish that the relatives who I’d be most interested in communicating with in an emergency had smart phones to receive text messages. Due to advanced age in one case and being anti-technology in another case (anti wifi, anti internet, anti camera), they don’t. My plan is to send a text message to another relative if I need to and hope for the best if I can’t reach my closest relatives. Thanks again for the JS8Call info.

      • 2

        Do you think they would be up for having one of those cheap pay-as-you-go phones from Walmart? It probably won’t cost them much if any if they don’t call or text people but they will have a backup form of communication with you if they need to.

        They are dumb phones without much internet capability, can be turned off except for when they need it in a disaster, and you can even sharpie over the camera so they don’t have to worry about that.

        Just a thought, but sounds like they probably wouldn’t even like that. Good that you have a backup way to connect with them through your other relative that can then check on them. 

        Another idea is to get the contact info of their next door neighbors who probably have a phone, or like the admin of the care facility if they are in one. Someone who is even closer and able to reach them better than that relative.

      • 2

        Robert, you make good suggestions. They do have that kind of cell phone, but they don’t keep it charged, and the supplier doesn’t support it any more. I do have contact information for a neighbor, which gives me some peace of mind. Also, we’re in the same general vicinity. Assuming an “ordinary” emergency, which would typically be weather related, I would be able to get there within a day or so. 

    • 3

      Wonderful post Josh! Having as many forms of communication as possible is key to easing worry and staying safe by receiving valuable intel.

    • 4

      Can I respectfully highlight one little or not so little issue with amateur radio,  I would add before I start I think people who can SHOULD get ham licences and gear and learn how to use it.  BUT a caviat is neccessary.  When you get a ham licence your Name /Call sign and ADDRESS is stored on publically accessible records, In many cases in Town halls, City halls, Public Libraries etc so anyone can access these records and find your address.  

      For 99% of us it wont matter or bother people. But in a few circumstances  some preppers put OPSEC and PERSEC above all else and dont want their locations made any easier than neccessary.    Just FYI in your decision making, but overall being a licenced ham user  is a massive positive for your emergency comms.

      • 4

        Some hams use PO boxes for their license to avoid that issue.

        On a related topic, I haven’t yet found a good option for keeping my address out of publicly available records when buying a house or registering to vote. If my address is out there anyway, having it also on my ham license seems like a small issue.

      • 2

        Over this side of the post you can simply check a box when you register to vote and they dont put your details on public records.

      • 3

        “Over this side of the post you can simply check a box when you register to vote and they dont put your details on public records.”

        In USA, each of the 50 states have different rules on how to run elections. In Florida, where I live, I would need to make a case that my life is in danger to prevent my information appearing online in easily searchable form. That includes name, address, birthday, party affiliation, phone number, and email. I’m not aware of any benefit to this invasion of privacy.


      • 2

        Bill – This is something I wish I would have known about before I got my licence. I have cleaned up my info as much as I can and have requested my call sign be hidden on some third party sites like qrz.com but it is still open to those who ask the FCC. 

        You are supposed to update your address when you move but I have not because I don’t want John Smith to be able to look me up and come give me a house call. He’ll go to my old address and not be able to find me. I know… I’m a bad ham. 

        For those who are going to get their license I recommend opening up a PO box at your local post office or even better set up a PMB (personal mail box) at your nearest UPS/FedEx store. Put that down for your address.

        The PMB or PO box is a powerful privacy tool to have at your disposal when you need to order something from a shady website, be an address you give out to the grocery store rewards program, and other places where you can have your junk mail sent to. Only give out your home address to trusted friends and family.

      • 3

        Can I also humbly suggest that those with privacy concerns investigate and research STEALTH ANTENNAS for their radio gear.  I know many people who run cable antenna down the side of houses, or trees or use INTERNAL antenna.

      • 2

        When I’m walking the dog through a neighborhood and see a big ol’ antenna sticking 10 feet above the roofline on a house, I say to myself “They probably are a ham, and they probably are a prepper with gear”. 

        I’ve started to take my antenna off the roof of my car and will only put it up when I am going to use it. I don’t want someone rifling through my vehicle looking for expensive ham gear. And if they do, SURPRISE! It’s only a $20 Baofeng. 

      • 3

        I use a mag mount on my van,  my mobil unit is a President Grant 2 Export model it does HAM and AM/ FM/SSB  CB  in US UK and most european bands.    and even with that lot I rarely hear any Ham traffic, no CB traffic and only occasional PMR (frs) chatter.   I had 5 boafengs with better antenna and extra earth leads for the family members, but we never used them so I gave them away.     Even scanners are of limited benefit in the UK because just about every service is encrypted these days.

      • 3

        Sorry your area of the UK doesn’t have as much for you to listen to. When I was in high school I saved up my hard earned money and spent like $100 on a used police radio scanner. I never figured out how it worked and wasn’t able to listen to anything. So I know how it feels to have the radio but not have anything to listen to. 

        Luckily there is a lot of ham traffic around here once you know which frequencies and times people get on. 

      • 4

        I just got a private mailbox for my FCC address. The thing about your address being sold if you’re registered to vote in the US is true. The local election commission misspelled my middle initials as “Jo” instead of “JD” and then I found my address on all sorts of data brokers under “Joshua Jo Centers.” I was so mad I didn’t vote for a few years and used the PMB for everything.

      • 4

        “I was so mad I didn’t vote for a few years and used the PMB for everything.”

        I had similar thoughts. If I just stop voting I can keep my real address off the internet. I don’t think it’s possible to use a PO box or PMB for voter registration.

        But it’s not just voting. Any time you buy a house, everything about that transaction is public record. Your name, address, and how much you paid are all online as well.

        So yes, you can use PO box or PMB for FCC registration, and many people do. But anyone who wants your address can still look it up.

      • 3

        Every little bit we can do to reduce our public or digital footprint helps. Its also why I dont use Loyalty cards and never buy all my gear from the same outlets.   EG if I want to stock up on tinned goods I buy from 3 or 4 different stores so there is no digital footprint of me bulk buying. 

      • 3

        I’m with you Bill. It’s very hard today to be “invisible” but every little bit helps to reduce our digital footprint or attack surface. 

        When I buy things from a store with cash, don’t use a rewards card, and have my phone off I feel better than if I was using my credit card, a rewards card, and having my phone with bluetooth and other radios on. Will anything bad happen to someone who does the second option? Most likely no, but I just don’t care to tell 15 different companies that I was at Walmart on such and such date and exactly what I bought and have that be a permanent record.

        Eric – If this is something you are interested in, titling your home in the name of a Trust can be a powerful privacy and estate planning tool. All that will be seen on the county records side and what will be scraped by data brokers and published all over the internet will be the trust name, such as: “The My House Trust”.