What does a "unselected carrier" error message mean?

Question

The message goes like this:

We're sorry this is an unselected carrier. This call cannot be completed as dialed. You may designate a carrier to handle this type of call by calling that company or your Verizon business office during regular business hours. To place this call in an emergency, just dial zero.

Any help understanding the underlying process that creates this error would be appreciated.

Answer 1

It is a telephone service message for the end user. It could be provided when multiple carriers are necessary to complete the call. You always have at least the local carrier directly managing the phone. For long-distance calls, it is possible to select another carrier where both carriers cooperate for the call completion. In your instance, I guess an automatic selection is used but has been disabled. Or it could be also that a wrong carrier code has been dialed for this particular call.