"SMS delivered" on some SIMs but not others

When I look at some SIMs, I see a “SMS delivered” event, and others, I do not. It’s possible these are different slightly different cell modems, is that message actually being generated by the cellular modem?

I believe that is partly dependent on the local carrier. We request a delivery receipt from the network for every SMS we send and usually the local carrier does send that back but sometimes it might not be honored. If you’re seeing two SIMs on the same carrier and one is consistently giving you those events while the other one isn’t we may want to drill down into that more to make sure there’s no underlying issues on our end causing that.

Thanks Reuben. It appears not to be SIM-specific. On a single SIM/modem combination (notice the green box), 5 days apart, you can see sometimes it says “SMS delivered” while other times it does not. Per its status page, I believe this device has always connected to CARRIER: AT&T Mobility APN: hologram

Happy to share device IDs, etc. in a private message.

I also just noticed that the events are not always in chronological order (notice the red box). Not sure if this is known/expected, I just never noticed before. This is for my GPS tracker + kill switch product.


Yeah can you DM me some device IDs and we’ll take a look in our logs? Have you confirmed the message was actually delivered to the device on your end?