Scammers can fake their caller ID info, and using the number they're calling seems to be a popular trick. For more information see any of the many article links at https://www.google.com/search?q=caller+id+my+own+number, for example https://www.consumer.ftc.gov/blog/getting-calls-your-own-number.
Comcast won't let you block your own number, so there's nothing you can do about this without resorting to 3rd party hardware.
Hello @nicholasbulpin, thanks for reaching out to our Forums! The information @BruceW provided is correct and I hope it was helpful. Please let us know if you have any further questions, we're here to help.