When phone notifications aren’t coming through, there’s a couple things you can try on your own, and plenty that the PagerDuty Support team can look into to help out.
First and easiest, I recommend adding the PagerDuty vCard to your phone. Some cellular providers block calls that they interpret as spam, and having the contact information on your phone is a good way to get those calls to come through.
Next, you can test the phone notification feature by navigating to your User profile in PagerDuty. On the Contact Information tab, your phone number will be listed, and there should be a Test link in that row, to the right.
If phone calls still aren’t coming through, reach out to the Support team at firstname.lastname@example.org. It’s most helpful if you have an example Incident that attempted to call your number within the last 48 hours. The more examples the better, too. If you want to create a couple test Incidents that attempt to notify you, there will be lots of logs to pull to investigate.