How do I determine owner of number receiving texts from my phone?

[RhinoCan]

I was going through my usage history on my phone and found something very odd: my phone sends text messages WITHOUT my participation!

Every day, it sends 5 texts at 1 minute intervals to the very same 4 digit number. It is NOT me that is sending those texts! I often go weeks without sending a single text and these are often being sent when I'm asleep. The phone is right beside me when I sleep and I'm sure no one else used it while I was asleep.

I'm puzzled by how a 4 digit phone number works. Shouldn't it have at least 10 digits here in North America to be connectable? (I'm in Ontario, Canada.)
The texts do NOT appear in my text history so I have no idea what is being sent. Is there any kind of reverse lookup that would tell me who owns this 4 digit number? If I knew who was receiving these texts, it might help me determine what's in them.

I suspect there is some kind of malware on the phone that is automatically sending texts every day for some unknown reason. Or maybe an app that I installed is misbehaving. I get all my apps from Google Playstore but I know that is no guarantee that the app is harmless.

The phone is a Pixel 3 running Android 12.

 

[Hadron]

Short numbers like that are often used by your service provider, but also by other companies or organisations. If they aren't showing up in conversations they may be your service provider. Where did you see them?

SMS was originally a communication between phone and network, and the ability to send messages to other people came later. So there can be innocuous hidden messages. But 5 per day sounds a bit unusual. Is there anything odd in your bills?

 

[RhinoCan]

The SMS messages aren't costing me anything since my plan has free texting so cost it not the issue. However, it bothers me greatly that my phone is sending texts without me knowing about it! It's even worse that I have no idea how these messages are being sent or what the message content is. This feels like some kind of malware doing something without my knowledge. I only became aware of these messages when I looked at my usage history the other day for the first time in many months.

I installed Avast for Android and scanned but it found nothing problematic. Yesterday, I also tried sending my own text to the 4 digit number - "How are you?" - but have not received any answer.

I would like to figure out what these messages say, who is getting them and how they're being sent because I'm not sending them myself, at least not consciously. (It may turn out that these messages are harmless and are being sent automatically as some normal part of my phone contract using some clause deep within the Terms of Service but I'm not aware of anything like that.) If I can't get any answers in forums, I'll have to take this up with the company providing my cell service.

 

[AugieTN]

What is the 4 digit phone number?

 

[ocnbrze]

usage history? where are you looking for this? is it this, Welcome to My Activity?

 

[Hadron]

If they were system messages of some sort they'd not cost you anyway. But I wanted to make sure there was no "premium messaging" scam going on, since such things do exist (Short code - Wikipedia).

We probably need to know some of the numbers and your service provider to have any chance of finding out what exactly these are.

 

[Clementine_3]

Text stop to the number, that is supposed to, well, make them stop. Not sure though since it's actually sending from your phone? What is the number as @AugieTN asked?

 

[RhinoCan]

Sorry for the long delay in replying; life's been frantic the last couple of weeks!

The number to which the SMS messages are being sent is 7723. The service provider is Koodo Prepaid here in Canada.
My brother has the same kind of account at the same provider so I looked at his usage data and his phone is ALSO sending SMS messages to 7723. The pattern is a little different but there are daily messages on his account just like mine.

 

[AugieTN]

Usage reporting showing texts to 7723 that I didn't send (I'm roaming in the US) | Koodo Community

 

[RhinoCan]

Thank you, Augie! I've turned off the SMS messaging for Google, Google Play Services, and Phone just like the guy who created the post. I also sent STOP to 7723. I'll check in a couple of days and see if that has worked. If it does, I'll turn the three apps back on, one every few days, until the messages start sending again to figure out which of them is the culprit. I'll post back here when I've figured it out.