PagerDuty phone and SMS notifications can come from varying numbers based on your country and other variables. The best way to ensure that you’re receiving a notification from PagerDuty is to download the PagerDuty vCard. The vCard is an up-to-date file containing the numbers that PagerDuty notifications can come from, and you can import it into your computer or smartphone contacts. We highly recommend downloading the vCard and keeping it updated, as it is subject to change.
If you're experiencing issues receiving SMS messages from short codes, your phone may be blocking short code messages, or your carrier may need to enable short code messaging for you.