Why did my iPhone ringtone change for an unknown number?

Perhaps it was a FaceTime call, which has a different ringtone.

Is it possible the call came through a different app, like WhatsApp, Messenger or something like that. 3rd party apps, wouldn't use the ringtone you've selected for cellular calls.

brynnalicious wrote:

i got a phone call from a number i dont know and its from my state and thats normal, just spam, right? but the weird thing was that it was a different ringtone than my normal ringtone. my ringtone isn't one people usually have, my ringtone is the michael myers theme and when this number called, it changed to the default ring tone. it was so weird. i wanted to check to make sure my ringtone didn't change, so i called and texted myself on my other device and it was the same ringtone it always is, michael myers theme. why did it change for just ONE number?? and the number isn't in my missed calls either. tripping me out help meee

Is the number in your Recents?

You said it didn't appear in missed calls. Hence why I asked if it could be from some other service.