Am I under active attack by cell network?

Questions
1

Howdy all,

I’ve had an unusual situation unfold, and I’m wondering if I’m in the middle of some active attacker situation. I missed a call from a 1-800 number (number A) which left a difficult to understand voicemail. My best understanding of the voicemail was that they were claiming to be a credit union calling for NOT_ME, and to call them back at a local number + an extension (number B).

I looked up number B and found both numbers listed on the website of a local credit union. I feel confident the website is legitimate. So I tried calling number B + what I thought the extension was (I had it wrong). Immediately once I pressed the button to call number B, I got a notification saying that I missed a call from a number from a different state (number C). I was willing to believe that was a coincidence.

After re-listening to the voicemail to figure out the correct extension, I called number B again. Again, immediately once I pressed the button to call number B, I got a notification saying that I missed a call from number C. I successfully got through to someone and told them I’m not the person they’re looking for and that as far as I know, I have never done business with them. They said they’d remove my number. I didn’t give any personal information, and I think I avoided answering any questions with “yes” or “no” (but I’m having doubts about that now).

I haven’t been able to find out much about number C. I confirmed that no one in my household does business with this credit union. I’m worried that this is an indicator of some kind of attack (SS7?) and that despite my best efforts I may have screwed up (was the call intercepted? is my voice going to be cloned for something?).

I am on GrapheneOS, have 2G network protection enabled, and have my preferred network type set to LTE only. I set it to LTE only based on the recommendations from Divested, which appear to still be maintained and still recommend this. It also is mentioned on the GrapheneOS website as being intended to reduce attack surface, so this doesn’t seem like a misconfiguration on my part.

Does anyone know if this seems like an indicator of some new (or old) attack? Is there somewhere I should be reporting this? Are there steps I should be taking in case my voice has been cloned?

2

This sounds like a simple wrong number. It is possible someone fat fingered your number or if you recently acquired this number, the former owner of it may have been a customer.

As to the weird behavior of receiving missed calls as you called the credit union; that could be many things including some weird bug in your phone. In any case, none of this sounds like some sort of complex attack.

3

I’d possible invoke Occam’s Razor.

  1. Wrong number
  2. Spoofed phone call

Personally, unless I’m expecting a call, they can hit my voicemail, and I’ll decide if it makes sense to call back.