I've had the same problem: 49 sms sent in a 4-day period to 7723. It stopped simply because I ran out of sms in my 50 min\sms plan.
Device is a Samsung Galaxy S9, started right after the Android Pie (One UI) update. And again after a minor update 2 weeks later.
So, one week in my monthly plan, I couldn't send any sms. And no notification or "delivery failed" status either (using Android Messages as texting app), so I've been sending texts for the past 2 weeks without knowing that they weren't delivered. This may be another issue though.
It seems fine now, I removed the dialer's sms access, didn’t find the visual voicemail setting in my app though. A moderator also credited back 50 sms, so it's working again.
It may be the OS or the device or the dialer's fault, but, I mean, Android has about 85% market share (or around 50%, not sure, but iOS users have had similar problems with Public Mobile anyway with new devices), I have the stock dialer and we've seen this with the following manufacturers: Samsung, Google, Xiaomi, OnePlus, ... So probably not hardware related, but software. And Public Mobile may only be the provider, but the service is used mostly on these kind of devices (i.e. smartphones).
But what is surprising is that Public Mobile seems to be the only provider with that problem. I haven't looked through other providers' forums, but I wouldn't be surprised at all if Public Mobile is the only one. I have been with Rogers prepaid for over 10 years and never paid for this. Asked someone who is currently with Rogers prepaid with the exact same device and update and nothing was charged. At the rate those were sent and the average price for sms with prepaid service in Canada, it's around 100$/month (12*30*0.30$), again, pretty sure no customer from any other company would pay this and there are nearly 4 million prepaid customers in Canada, a bit more if we include all on postpaid with a limited texting plan.
How many clients have a limited sms plan with Public Mobile and how many have a recent\updated Android OS (7+) on a 8$/month plan? It may not be a common problem, but it exists nonetheless.
These sms aren't sent to other clients (10-digit number), what we typically refer to when subscribing to a texting plan, but system ones, probably sent to the provider, as it seems to be for visual voicemail, and this is a provider's functionality. So, if it's true that these are only send from the device to the provider (i.e.: Public Mobile), when we have a plan that says "50 outgoing sms", is it from the device to the provider or from the provider to a destination number (same or different provider)? I think a good case could be made for the latter. Not sure if it's a good analogy, but IPTV providers are not counting the terminals' usage when the traffic doesn't leave the network.
And even Public Mobile doesn't seem to know in it's own systems. It logs them differently by identifying the "usage type" as "minutes" rather than "sms". I started another thread about the notifications, apparently, other clients get sms from 611 when usage reaches a certain level. I didn't get it. So, in my opinion, the notification system is not counting them, but billing system is. I'm pretty sure there is a problem somewhere. At the minimum, consistency would be appreciated.
https://productioncommunity.publicmobile.ca/t5/Plans-Add-Ons/Notification-when-out-of-SMS/m-p/331737...
I think that Public Mobile should make the distinction, it should be doable as they are already identified differently in usage history, just the fact that all other providers in Canada seems to be doing it differently should be sufficient.
