[Samsung Epic 4G Touch] phreich:
Looks like these are indeed a "system generated texts" caused by "Sparkle".

Hey folks,

I know this is an old thread, but the issue is still ocurring, so rather than start a new thread, I thought it better to keep adding to the knowledge accumulated here....

I just found out I am getting these 8737 messages too. Because I have the Sprint/GoogleVoice integration turned on, and my SMS messages are therefore routed through Google Voice, it is doing its job and has hidden these messages in the SPAM folder in Google Voice. I am grateful for this, as some of these messages are arriving in the wee hours of the morning. The rest of the messages come through and show up on my phone in the stock Samsung SMS app.

Anyway, I also decided to take a look at this, and I think the previous poster is correct -- that it is related to Sprint using the "Sparkle" services. I am not sure what Sprint "imposed" apps are integrated with Sparkle, but it seems clear that the messages all start with LL:, a string of numbers, then the registered Sprint cell number, followed by more data. I suspect that the numbers following "LL" are the phone's location, or "L"atitude and "L"ongitude. I haven't figured out what triggers the messages yet -- they seem to come at random times, but could be caused by cellular radio restarts as one previous poster has suggested.

In case it helps others to determine the pattern of this stuff, here's my setup on Sprint:

I have stock up-to-date firmware on a Sprint Galaxy S7, and still have the stock Samsung SMS message app handling my regular SMS messages on the phone. I don't have any secondary SMS message handling apps installed, but do use both Whatsapp and Telegram as alternative message programs to communicate with friends and family who use them, but they aren't SMS or MMS -- they do their own encrypted thing and leave regular SMS messages alone. I do have the Sprint integration with Google Voice enabled as I prefer Google Voice's free services over having to pay Sprint for their "premium" voicemail to get message transcription and voicemail text notifications, and improved voicemail handling. I also appreciate the decent SPAM caller and voicemail handling that Google Voice does. I rarely have any SPAM calls or texts come through due to this. I have no problems with the Sprint-GoogleVoice integration. I do have a friend that did have a problem, and we had to disable it and re-enable it to get it working properly -- but he is not getting these strange SMS messages from 8737. I just upgraded last month from a Galaxy S4 (running Android 5.0.1) to my S7 (Android 7.0), and it seems the messages started to appear about that time -- so maybe that's a clue. Before activating the phone on my Sprint account, I did a factory reset -- so the phone started out, and remains purely "stock", other than the apps I have installed. I don't use an Airave device currently so that's not the cause either.

One thought -- possibly the other SMS message handlers that previous posters are talking about also have "Sparkle" services integrated in them, which is why it only sometimes seems to be related to those apps being present? This is just a SWAG on my part.

As long as Google Voice continues to move these messages aside as SPAM and I don't have to see them, it's fine by me. For those who continue to be plagued by these 8737 SMS messages, you might consider trying out the Sprint/GoogleVoice integration and benefiting from it's SPAM call and text filtering. Just for grins, I may try marking the 8737 SMS messages as "not spam" in Google Voice and see if they actually appear in the Samsung SMS app on the phone. It's possible they won't, but instead get intercepted by some "Sparkle" integrated Sprint app on the phone. If I do this, I'll update this posting with the results.

Why am I staying with Sprint and putting up with the "Sparkle" integration stuff? It's because I've been with Sprint since the mid-90's and stayed with them because I have continuously gotten a good deal on phone and data plans and they have and continue to treat me very well because of my longevity with them. I still am on a old grandfathered "Framily" plan with the max discount, and continue to enjoy completely unthrottled/non-"prioritized" unlimited LTE/4G data (See P.S. below for info on Sprint's data "prioritization" scheme.)

Good luck to everyone still trying to "sleuth" this one out.....

Philip

P.S. Some of you longer term Sprint account holders may remember when Sprint had ads saying their not throttling data on unlimited plans was one of the reasons folks should sign up with them? Well, their newer plans don't make this promise and implement tower "prioritization" after a line has used 20GB of data in the service month -- while not exactly "throttling", the effect is the same if a heavy data user tries to use 4g/LTE data when connected to a busy Sprint tower -- they are put at the "end of the queue" for 4g/LTE data access and will instead only get 3g data until an available 4G slot opens up on the tower. The difference between this and full "throttling" is that if the tower being accessed isn't busy, since there are open 4G access "slots" available, the heavy data users then are connected to 4g/LTE data. I also noticed that the current iteration of Sprint's newer plans aren't offering permanent rates at the currently advertised pricing -- instead after a year they revert to higher pricing -- this is a new and I think a bit underhanded marketing tactic to get their customers to always "upgrade" to the newest plan at the then-prevailing monthly rates -- potentially also requiring a contract term agreement.

Bottom line, if you have a cost-effective older unlimited plan, don't upgrade to the newer plans if you are a heavy data user, or want your monthly rates to continue to be permanent where they are. Because the older plans "explicitly" mention rates and that they are truly unlimited, they remain exempt from this "prioritization" scheme. The tradeoff here is that these older unlimited plans usually did not include any data tethering without paying extra for it, while the newer plans include, I recall, 10GB of data tethering use at 4G/LTE speeds, after which the data tethering (only) gets throttled to 2G speeds, untethered data use continues unthrottled until the 20GB "prioritization" scheme takes effect.