xMatters conference bridges: unrecognized numbers

Question

I noticed some phone numbers that I don't recognize joining an xMatters hosted conference bridge, or when reviewing my call logs. Why is this happening, and are they a security risk?

Environment

All versions of xMatters

Answer

If you see an unusual number joining an xMatters conference bridge or in your call logs, it could be because the number is restricted, blocked, or unknown.  The message type provided by the phone carrier is converted into a number, which is what you might see on the call or in the call logs. Here's a list of the messages and their corresponding numbers:

These messages are part of normal carrier operation and are generally not a security concern. If you see a number that's not listed in the table and would like to investigate further, submit a request to xMatters Support.