Why are the caller IDs of the incoming notifications I receive incorrect?

Question

Sometimes I receive notifications from a different number than I'm expecting — is there a reason why this is happening?

Environment

• All versions of xMatters

Answer

When xMatters generates a call, Caller IDs are passed from our provider to their downstream carriers. All xMatters calls submit the Caller ID using standard formatting.

However, for international calls, different carriers vary in their preferred caller ID formatting. Since calls may traverse through several networks before reaching their destination, the caller ID information may be altered along the way. 

There are three main circumstances that cause a caller ID to be displayed incorrectly:

1. A caller ID may be modified along the way by any intermediary carriers.
2. The caller ID may be lost or replaced when crossing international borders.
3. Local regulations sometimes dictate that a caller ID be modified.